Questions that begin "Is it ok to _" are often asked and I believe it is helpful to ask "how now shall we live?". However, from a theological standpoint are these questions of primary importance when considering the whole of and heart of Christian doctrine?
I think these kind of questions often betray a deeper problem: a lack of understanding of the primary importance questions of doctrine that you mention. They often stem from an understanding of Christianity as a set of cultural norms or a rulebook of right and wrongs instead of hearts that have been remade from stone to flesh.
I do think it is valid that we field them but our emphasis should always be on pointing people to the more foundational truths that enable us to discern the answers to lodes endless trivia.
We ask "is it okay to _" because many Christians were raised on moral religiosity instead of principles of Christian decision making. Based on the second greatest commandment to love our neighbors as ourselves (Matthew 22:39), Jesus calls everyone to love every human being they come into contact with (including themselves). And to love means to seek what is best for myself and to ask what is best for the other, and to be honest if we are lying to ourselves about what we say is "best", while not being intellectually lazy and not examining from as many angles as is possible what is best in any given situation.
And no, these ethical questions may not be the most important because they may be more founded in "how far can I go in this one act before GOD is angry/disappointed?". But the truth is that GOD is not offended by anything that doesn't first hurt us, and that if we really allow a pure love of GOD, self and neighbor to be our new ethic then we might be closer to actually living how we were supposed to.
For a really good discussion of this read Thomas aquinas' summa theogica or kierkegaard's works of love (where he contrasts doing works of the law with doing works of love) or even augustine's comments on how Christians ought to live by the spirit and not by the letter.