If by the word "doctrine" we mean "official teachings of the Church," then bcspace is perhaps somewhat correct. However, that would mean that we cannot point to the scriptures to define doctrine--rather, doctrine would be the interpretations of scripture officially sanctioned by the Church.
It seems clear to me, however, that the Church uses the word "doctrine" in a manner that means far more than simply "official teachings of the Church." I addressed this problem of the term "doctrine" in a recent issue of Element. You can read a portion of it here: "The Challenges of Mormons Defining Mormon Doctrine for Mormons; or, Is It Mormon Doctrine that Mormon Doctrine Is True?"
This is absolutely incorrect. Doctrine resides in the scriptures (and modern revelation) but only the prophets can interpret it or "tease it out" so to speak. Therefore, doctrine is more important than scripture. See also 2 Peter 1:20
For example, according to John 3:5 a man must be born of the water and the spirit to enter into the kindgom of heaven. The LDS Church interprets water as water baptism. Most of the Protestant and Evangelical churches interpret it as physical birth. One would not know what LDS doctrine is on the subject without seeing a publication on it. Hence, published doctrine is more important than scripture and this is the way the Church has always considered it and it's foundation is the notion of the Restorration and the need for living prophets and apostles. Anyone who thinks otherwise does not really accept the Restoration or the need for living prophets.
So with the LDS Church, every real, virtual, and memorized copy of the scriptures on planet earth could disappear and we would still be good because we have modern prophets.
Bc, a lot of stuff has been published. If you look at recent Priesthood manuals, it seems as though polygamy never happened, yet we know that is not true.
If there is a conflict, doctrine is of latest date. I don't see any denial of plural marriage and I still see the doctrine referenced. Since we don't practice it among the living, I don't think it unreasonable to go for miles without seeing it though.
Could it be there are various, yet to be categoried, levels of doctrine? You mentioned esoteric doctrine. I imagine there is even a more secret deep level doctrine which you have to be anointed and keyed at the highest level in order to receive it. Then there is street level doctrine.
Sure. But ultimately, you must accept all true doctrine to be saved in the sense the Church exists for.
Seems much easier to go with the LDS Canon.
Can't for the reasons mentioned above; private interpretation.