How do we go to Heaven? Faith in Jesus or membership in a church?
Who is our Helper and Advocate? Holy Spirit or Mary?
Who is our priest? Jesus or a man?
Do we have complete forgiveness of our sins or is there something we must do to atone for those sins? Col 2:13-14 or indulgences?
These aren't either/or propositions. "Upon this rock I will build my church." Faith in Jesus and membership in Jesus's church go hand-in-hand.
Who is our Helper and Advocate? Holy Spirit or Mary?
Advocate with a capital "A" is the Holy Spirit. We can all be intercessors (small "a" advocates) for one another. Mary is the intercessor par excellance.
Who is our priest? Jesus or a man?
Jesus, our High Priest, instituted the Eucharistic sacrifice before His Sacrifice on Calvary. Those who "Do this" as he commanded are priests in a ministerial sense.
Do we have complete forgiveness of our sins or is there something we must do to atone for those sins? Col 2:13-14 or indulgences?
Forgiveness of sin and the temporary punishment for the sin are two different things. Ask David:
13Then David said to Nathan, “I have sinned against the Lord.” Nathan replied, “The Lord has taken away your sin. You are not going to die. 14But because by doing this you have shown utter contempt for the Lord, the son born to you will die.” 2 Sam. 12:13-14
And forgiveness of our sins does not preclude our suffering to conform us to the Lord, as Paul notes:
"24 Now I rejoice in my sufferings for your sake, and in my flesh I do my share on behalf of His body, which is the church, in filling up what is lacking in Christ’s afflictions. Col. 1:24
7 It is for discipline that you endure; God deals with you as with sons; for what son is there whom his father does not discipline? 8 But if you are without discipline, of which all have become partakers, then you are illegitimate children and not sons. 9 Furthermore, we had earthly fathers to discipline us, and we respected them; shall we not much rather be subject to the Father of spirits, and live? 10 For they disciplined us for a short time as seemed best to them, but He disciplines us for our good, so that we may share His holiness. 11 All discipline for the moment seems not to be joyful, but sorrowful; yet to those who have been trained by it, afterwards it yields the peaceful fruit of righteousness. Heb. 12:7-11
Do you have other questions I can help you answer and understand?