Ah, where to start...
You correctly paraphrased Revelation. The key is that Revelation talks about adding to "THIS book." To what book would John be referring? You seem to think it's the Bible, but of course that can't be so, because the Bible didn't even exist at the time, nor was it really even in the works. Second, even if he was talking about the Bible (which he obviously was not), it has undergone countless changes throughout the years, adding and subtracting to and from what is considered canon. The Bible you use today has undergone numerous additions and subtractions, so I guess by using it you're in the same camp as those who use the Book of Mormon.
Of course, however, you're not, because logically the book to which John is referring can only be the Book of Revelation itself. It's a warning about changing or editing the revelation that he received. Of course, Mormons have not done this, because they believe the Bible is the word of God and believe in Revelation, having not changed it.
Your next point quotes Galations, regarding the preching of other gospels. Mormons do not preach other gospels, they (claim to) preach the true gospel of Christ. Unfortunately, many aspects of the gospel had been or were unclear - this really can't be refuted, how else can one explain all the various sects? Mormonism teaches what they believe to be the true gospel of Christ, unchanged (as Paul requires). Of course, this is what all the other Christian faiths do as well - they teach what they believe to be the true gospel, but due to the uncertainties in the Bible, the best they can do is teach their personal interpretation. Mormonism, on the other hand, at least claims to have input from God in clearing up these uncertainties. All other faiths, by their own admission, can only hope to be preaching the true gospel that Paul speaks of. Nothing was added.
As for visiting the Americas, in John 10:16 Jesus says that he has other sheep who will hear his voice. This can easily be seen as Him saying that he is going to the Americas. Oh, and your "recollection" of the Book of Mormon is (shockingly) incorrect - Christ does appear to the people in the Americas in the flesh. This is because he has been ressurected.
Next, you say the Bible doesn't address Baptisms for the Dead? Check out 1 Corinthians 15:29 (Or else what will they do who are baptized for the dead? If the dead aren't raised at all, why then are they baptized for the dead?). Sounds like the saints were performing baptisms for the dead, and from the context of 1 Corinthins 15, it sounds like the the leaders of the church approved of this practice.
Finally, you are correct that we should test the spirit to see if something is from God. However, it seems as though you have failed to actually apply this admonition. Your convictions seem to be based upon your interpretations of text and on what you have been fed by anti-mormon sources. Have you ever actually read the Book of Mormon to test it by the spirit, by actually praying and asking the spirit to let you know whether or not it is true? It seems to me that you are using the tests of man and not the spirit to reach your conclusions.
The Book of Revelation, while it appears as the last book in The New Testament there was no New Testament in place when John wronte the Book of Revelations. The canon was not established until the late 300's. In 397 AD, at the Council of Carthage, the books of Hebrews, James, 2 Peter, 2nd and 3rd John and Jude were added to the canon for the first time. In addition, the Shepehered of Hermas, the Leter of Barnabas, the Gospel of the Hebrews, the Reveation of Peter, the Acts of Peter, the Didache, the Teaching of Twelve, and the Apostles were all removed from the Canon. To interpret that verse to mean that one can't add to the Bible would mean that one would have to throw out the books all of the books added in 397. In fact, at the time that John wrote the Book of Revelations, the only books that were part of the Canon were Luke, Romans, 1st and 2nd Corintians, Galations, Ephesians, Philippians, Colossians, 1st and 2nd Thessalonians, and Philemon. So, if you stick to your interpretation of that scripture in Revelations, then you would have to throw out Matthew, Mark, John, Acts, 1st and 2nd Timothy, Titus, Hebres, James, 1st and 2nd Peter, 1st, 2nd, and 3rd John, and Jude. You would have to toss out well over half of the books in the New Testament. I don't think that you want to go there.
Even Moses in the Song of Moses from Deuteronomy warns direly that anyone who adds to the Word of God is in huge trouble.
Wow! So, now we'll have to throw out almost all of the books in the Old and New Testaments since they came after Deuteronomy.
Please, you really need to stop. You've callously taken the opportunity of a thread about the tragic shooting of a servant of God to attack the faith of the murdered young man and that of his family. I think that if you examine such behavior you will not find it to be consistant with what is commonly believed to be Christian behavior. I hope that you can refrain from such further behavior and go find other more interesting threads in which to post your opinions.
Yes, and we have no record of any man adding to the book of Revelation since its SELECTION for the Holy Bible, especially the Church of Jesus Christ of Latter-Day Saints and you well know it. Perhaps you should read your scriptures. They are written in pretty plain English and it is clear context that those words were included in the Book of Revelations for that Book alone.
As to the rest of your balderdash - well it speaks for itself and when you twist the plain Word of God the way you do, watch out.