It is a package deal, and I am stumped right at the beginning (her being sinless).
Yes, I think it is not possible to grasp this without going back to the identity of Jesus (upon which all the Marian dogmas are based). When she was proclaimed by the Church as the Theotokos by The Council of Ephesus in 431 A.D., it was for Christological reasons.
"“If anyone does not confess that God is truly Emmanuel, and that on this account the holy virgin is the “Theotokos” (for according to the flesh she gave birth to the word of God become flesh by birth) let him be anathema.” (The Council of Ephesus, 431 AD)
The Council’s insistence on the use of the title reflected an effort to preserve the teaching of the Church that Jesus was both Divine and human, that the two natures were united in His One Person (hypostatic union). One of the heresies rampant was an interpretation of the teachings of a Bishop of Constantinople named Nestorius. Some of his followers insisted on calling Mary only the “Mother of ‘the Christ’”. The Council insisted on the use of the title (in the Greek) “Theotokos,” (“Mother of God” or “God-bearer”) to reaffirm the central truth of what occurred in the Incarnation of Jesus Christ.
It was important to the early church that Jesus be understood to have taken “flesh of her flesh” (fully human as well as fully God). But it was believed that He would not have taken tainted flesh. Now you may say, Jesus could have cleansed her flesh from original sin at the time of His conception and growth in the uterus, and this is true, but for Him to be “born of woman, under the Law”, His body had to come fully from her flesh.
I would hold St. Paul’s oral teaching as divine if I heard, just as I when I read it.
Yes, of course. those whose hearts are quickened by God recognize HIs truth immediately! What you don’t hold is that those teachings were preserved infallibly in the church by the Holy Spirit. You seem to believe that all that was relevant was committed to writing, though the writings do not say this. It is a modern innovation designed to jettison the authority appointed by Christ.
Yes, but we are talking about their roles after Scriptures have “caught up” to oral.Unless of course one says revelation is still ongoing, and more to be written (and while technically not calling it “scripture”, still same as far as from God, and that infallibly, to be obeyed/believed).
No, the CC does not teach that revelation is “ongoing”, just our understanding of it. Doctrinal development is about applying the once for all deposit of faith to the current circumstances.
Yes, the Church has the gift of infallibility to prevent the faithful from passing through the gates of hell, and we are called to obey the authority appointed by Christ as if they are Christ.