You seem to be putting a lot of weight upon Jesus speaking about taking "disputes" to the church. You mentioned that part three or four times in this comment alone. I went to the place in Scripture where Jesus spoke about this and here is the context:
And if thy brother sin against thee, go, show him his fault between thee and him alone: if he hear thee, thou hast gained thy brother. But if he hear thee not, take with thee one or two more, that at the mouth of two witnesses or three every word may be established. And if he refuse to hear them, tell it unto the church: and if he refuse to hear the church also, let him be unto thee as the Gentile and the publican. (Matthew 18:15-17)
Rather than saying we should take all our disputes to the "church", Jesus very clearly is talking about when a brother does something wrong, either personally to you or when he is sinning in such a way that the "world" is noticing. As should be the case, you must go to the brother at fault and take it up with him, one on one. But if he refuses to hear you and repent of the sin, you should then return with one or two others and confront him. If he still refuses to repent, then you should tell the "church" - your local assembly of believers where the offending brother also attends. If after he continues in the sin and doesn't listen to his fellowship of believers, then the local assembly should expel him from their fellowship.
Now, Jesus seems to be speaking about individual behavior of each member of the church and how overt wrong behavior is to be dealt with, NOT, as you seem to infer, that one, global "church" organization is to be an arbiter of what is and isn't truth. That is why God gave us the Holy Scriptures - so that it is the authority by which truth can be determined for the faith. What Jesus taught, the Apostles taught and what they taught they wrote down for all time through the leading and inspiration of God. The entire "church" - the body of Christ - is to be held to that same standard of truth. The leaders of the local assemblies have no more authority to determine what is truth than some global hierarchy does because God has already told us what is truth and what is false. This revelation is complete and ALL truth claims must be measured by the God-breathed Holy Scriptures.
No man or organization can circumvent nor contradict what God has set forth no matter what "history" he clings to. When Paul said the church is the "pillar and foundation of the truth" (I Timothy 3:15), he most certainly meant that the believers who make up the church, the body of Christ, must support and uphold the truth as God has revealed it to us. Barne's Notes on the Bible explains this well:
Which is the church of the living God - This seems to have been added to impress the mind of Timothy with the solemn nature of the duty which he was to perform. What he did pertained to the honor and welfare of the church of the living God, and hence he should feet the importance of a correct deportment, and of a right administration of its affairs.
The pillar and ground of the truth - There has been no little diversity of opinion among critics whether this phrase is to be taken in connection with the preceding, meaning that "the church" is the pillar and ground of the truth; or whether it is to be taken in connection with what follows, meaning that the principal support of the truth was the doctrine there referred to - that God was manifest in the flesh. Bloomfield remarks on this: "It is surprising that any who have any knowledge or experience in Greek literature could tolerate so harsh a construction as that which arises from the latter method." The more natural interpretation certainly is, to refer it to the former; and this is supported by the consideration that it would then fall in with the object of the apostle. His design here seems to be, to impress Timothy with a deep sense of the importance of correct conduct in relation to the church; of the responsibility of those who presided over it; and of the necessity of care and caution in the selection of proper officers.
To do this, he reminded him that the truth of God - that revealed truth which he had given to save the world - was entrusted to the church; that it was designed to preserve it pure, to defend it, and to transmit it to future times; and that, therefore, every one to whom the administration of the affairs of the church was entrusted, should engage in this duty with a deep conviction of his responsibility. On the construction of the passage, Bloomfield Rosenmuller, and Clarke, may be consulted. The word "pillar" means a column, such as that by which a building is supported, and then any firm prop or support; Galatians 2:9; Revelation 3:12. If it refers to the church here, it means that that is the support of the truth, as a pillar is of a building. It sustains it amidst the war of elements, the natural tendency to fall, and the assaults which may be made on it, and preserves it when it would otherwise tumble into ruin.
Thus it is with the church. It is entrusted with the business of maintaining the truth, of defending it from the assaults of error, and of transmitting it to future times. The truth is, in fact, upheld in the world by the church. The people of the world feel no interest in defending it, and it is to the church of Christ that it is owing that it is preserved and transmitted from age to age. The word rendered "ground" - ἑδραίωμα hedraioÌ„ma - means, properly, a basis, or foundation. The figure here is evidently taken from architecture, as the use of the word pillar is. The proper meaning of the one expression would be, that truth is supported by the church. as an edifice is by a pillar; of the other, that the truth rests "on" the church, as a house does on its foundation. It is that which makes it fixed, stable, permanent; that on which it securely stands amidst storms and tempests; that which renders it firm when systems of error are swept away as a house that is built on the sand; compare notes on Matthew 7:24-27.
The meaning then is, that the stability of the truth on earth is dependent on the church. It is owing to the fact that the church is itself founded on a rock, that the gates of hell cannot prevail against it, that no storms of persecution can overthrow it, that the truth is preserved from age to age. Other systems of religion are swept away; other opinions change; other forms of doctrine vanish; but the knowledge of the great system of redemption is preserved on earth unshaken, because the church is preserved, and because its foundations cannot be moved. This does not refer, I suppose, to creeds and confessions, or to the decisions of synods and councils; but to the living spirit of truth and piety "in" the church itself. As certainly as the church continues to live, so certain it will be that the truth of God will be perpetuated among people.
We all then, as members of this one body, are commanded to be the salt and light to the world and the upholder of the truth of the Gospel of Jesus Christ as God has revealed to us through His word and through the indwelling Holy Spirit. Not, as you seem to suggest, some governing hierarchy seated in one special place deciding what is and is not the truth. Christ most certainly DID establish his church and it most certainly IS guided by the Holy Spirit but it is a universal called-out assembly of individual believers who make up that body - the Bride of Christ - and we are guided by the Holy Scriptures which contain all the truth God has chosen to reveal to us and it is His word which is inerrant. The church rests on the truth, the truth does not rest on the church.
Has the RCC when it has claimed to speak infallibly, ever been wrong, even once? If so, that disqualifies it from being able to claim to be speaking for God
Well, this depends on the interpretation of whether one was speaking infallibly, and thus the denial that pope Honorius and others were guilty of such, as some charge.
And it also depends upon interpertinb what was meant, and as one RC basically said, since Rome defines what is right and wrong [and that there is no external and unchanging rule of faith for the Roman Catholic Church], then they cannot be wrong. What statements are infallible and what are not, as well as the level of obedience owed to to the ordinary magisterium can differ according interpretation, as well as what they mean. One pope or more can,
"declare, say, define, and pronounce that it is absolutely necessary for the salvation of every human creature to be subject to the Roman Pontiff,” (Pope Boniface VIII, Unam Sanctam 1302)
And,
"The sacrosanct Roman Church...firmly believes, professes, and proclaims that..schismatics cannot become participants in eternal life..unless before the end of life the same have been added to the flock; and that and that no one, whatever almsgiving he has practiced, even if he has shed blood for the name of Christ, can be saved, unless he has remained in the bosom and unity of the Catholic Church." (Pope Eugene IV, Cantate Domino, 1441)
And that
"subjection to the Roman pontiff is necessary for salvation for all Christ's faithful..."( Fifth Lateran CouncilSession 11, 19 December 1516),
Also,
"No one is found in the one Church of Christ, and no one perseveres in it, unless he acknowledges and accepts obediently the supreme authority of St. Peter and his legitimate successors." (Pope Pius XI, Mortalium Animos, PTC:873)
And which was understood by no less than the doctor of the church Thomas Aquinas (elevated 1567, patron of all universities and of students), to mean what it sounds like it means, that,
"It is also shown that to be subject to the Roman Pontiff is necessary for salvation." St. Thomas Aquinas, Against the Errors of the Greeks, Pt. 2, ch. 36 http://dhspriory.org/thomas/ContraErrGraecorum.htm#b38)
But having lost her unScriptural use of the sword of men, she latter "reformulates" this:
How are we to understand this affirmation, often repeated by the Church Fathers? [Cf. Cyprian, Ep. 73.21: PL 3, 1169; De unit.: PL 4, 509-536.] Re-formulated positively, it means that all salvation comes from Christ the Head through the (Catholic) Church which is his Body:
... Hence they could not be saved who, knowing that the Catholic Church was founded as necessary by God through Christ, would refuse either to enter it or to remain in it." (CCC #846)
And,
The Church recognizes that in many ways she is linked with those who, being baptized, are honored with the name of Christian, though they do not profess the faith in its entirety or do not preserve unity of communion with the successor of Peter. (Cf. Gal. 4:6; Rom. 8:15-16 and 26)
For there are many who honor Sacred Scripture, taking it as a norm of belief and a pattern of life, and who show a sincere zeal. They lovingly believe in God the Father Almighty and in Christ, the Son of God and Saviour. (Cf. Jn. 16:13) They are consecrated by baptism, in which they are united with Christ. They also recognize and accept other sacraments within their own Churches or ecclesiastical [Protestant] communities...
They also share with us in prayer and other spiritual benefits. Likewise we can say that in some real way they are joined with us in the Holy Spirit, for to them too He gives His gifts and graces whereby He is operative among them with His sanctifying power. Some indeed He has strengthened to the extent of the shedding of their blood...” (Vatican Two; Lumen Gentium 16)
While some RCs yet interpret this as referring only to baptized obedient Protestants who never heard of the claims of Rome, and thus most all need to convert to Rome to be saved, most recognize it as an affirmation of Protestants in general, the exception being those who really know Rome is the church founded by Christ but reject it, rather than referring to those who find her claim to be the OTC as Scripturally unwarranted.
Then there are those Catholics who see this “reformulation” as being contrary to the prior intent and understanding, which i think is the most warranted conclusion, and thus they deny the authority of Vatican Two and (some) even deny the validity of the recent and present pope, and so are held to be in a degree of schism by Rome which they see as deviating from her ancient faith.
In addition to statements which have been held as ex cathedra, which Bellarmine and others held Unam Sanctam was, are statements made in Rome's “ordinary and universal teaching power,” which are “to be believed as divinely revealed.” (Pope Pius IX, Vatican I, Sess. III, Chap. 3) But what statements belong to that category and the level of authority of this very statement (and whether everything that V1 declares is infallible) can also be subject to dispute.
And understandably so, as it would require that statements made in papal encyclicals and public proclamations be upheld consistently, such as condemns the proposition that “persons coming to reside therein [Catholic countries] shall enjoy the public exercise of their own peculiar worship,” while affirming the right of Rome to secular power and force, (Pope Pius IX, The Syllabus (of Errors)
And condemning in regards to schismatics, “that liberty of conscience must be maintained for everyone.“ (Quanta Cura, Encyclical of Pope Pius IX) And “that the State must be separated from the Church is a thesis absolutely false, a most pernicious error.” (Vehementer Nos [on the French Law of Separation, which in principle can be universally applied], Encyclical of Pope Pius X promulgated on February 11, 1906)
And then you have the ecclesiastical and papal statements affirming the use of torture against theological aberrants, such as by Ecumenical Fourth Lateran Council, 1215 (http://www.fordham.edu/halsall/basis/lateran4.asp), and affirmed by Thomas, as well as the papal bull Ad exstirpanda (http://userwww.sfsu.edu/~draker/history/Ad_Extirpanda.html), the reading of which is sufficient to see the point, and in which captured heretics are to be coerced into confessing their errors and accusing others.
The idea that the veracity of Rome is extensive leads to such approved teaching as that asserts,
“All that we do [as must be patent enough now] is to submit our judgment and conform our beliefs to the authority Almighty God has set up on earth to teach us; this, and nothing else.”
“...outside the pale of Rome there is not a scrap of additional truth of Revelation to be found.”
“He willingly submits his judgment on questions the most momentous that can occupy the mind of man-----questions of religion-----to an authority located in Rome.”
“Absolute, immediate, and unfaltering submission to the teaching of God's Church on matters of faith and morals-----this is what all must give..”
“The Vicar of Christ is the Vicar of God; to us the voice of the Pope is the voice of God. This, too, is why Catholics would never dream of calling in question the utterance of a priest in expounding Christian doctrine according to the teaching of the Church;”
“He is as sure of a truth when declared by the Catholic Church as he would be if he saw Jesus Christ standing before him and heard Him declaring it with His Own Divine lips.” —“Henry G. Graham, "What Faith Really Means", (Nihil Obstat:C. SCHUT, S. T.D., Censor Deputatus, Imprimatur: EDM. CANONICUS SURMONT, D.D.,Vicarius Generalis. WESTMONASTERII, Die 30 Septembris, 1914 ); http://www.catholictradition.org/Tradition/faith2-10.htm]
"The intolerance of the Church toward error, the natural position of one who is the custodian of truth, her only reasonable attitude makes her forbid her children to read or to listen to heretical controversy, or to by examining both sides of the question...
The reason of this stand of his is that, for him, there can be no two sides to a question which for him is settled; for him, there is no seeking after the truth: he possesses it in its fulness, as far as God and religion are concerned.” (John H. Stapleton, Explanation of Catholic Morals, cps. XXIII, Nihil Obstat. Remy Lafort, Censor Librorum. Imprimatur, John M. Farley, Archbishop of New York )
These words of Christ's should be enough to lay to rest the argument that the personal lives of Catholics priests, or any clergy for that matter, are irrelevant in the performance of their duties. If their lives do not demonstrate the fruit of repentance and a changed life, they can be considered false prophets.
The Roman Catholic response to this is to assert that wicked leaders like Caiaphas could speak truth in accordance with Divine promise, (Jn. 11:49-51) so it is condemnd as an error that “if the Pope were a reprobate and an evil man and consequently a member of the devil, he has no power over the faithful." (Council of Constance, Condemnation of Errors, against Wycliffe, Session VIII, and Hus: Session XV; DNZ:621, 617, 588)
However, unlike the old covenant with its physical kingdom and need of physical progeny to lay claim to being a high priest, under the new covenant physical decent is not the basis for authenticity (the church actually began in dissent from those who could lay claim to historical authority, and it excludes the type of men some popes were from even being church members, (1Cor. 5:11-13) let alone successors to Peter.
Rome has actually never followed the method used in selecting a successor for Judas (in order to maintain the original number: Acts 1:15-26; cf. Rv. 21:14, while there was no successor for the apostle James: (Acts 12:1,2) nor do her popes fulfill the requirements of personal discipleship of Christ, while it is presumed that men who were immoral even before they were chosen popes as well as during their reign, and who election by the Holy Spirit was much by politics, were valid successors to Peter, even if the Bull Cum Ex Apostolatus disallows the validity of even the Roman Pontiff if before their election they had deviated from the Catholic faith, which some bad popes, including sexually active ones, may be charged with doing.