The full text of 1 Timothy 3:2-3 is [NIV translation]:
“Now the overseer must be above reproach, the husband of but one wife, temperate, self-controlled, respectable, hospitable, able to teach, 3not given to drunkenness, not violent but gentle, not quarrelsome, not a lover of money.”
It seems you’re interpreting that as meaning “in order to be considered above reproach, the overseer must be (A) the husband of one wife, (B) temperate, (C) self-controlled, …”
However, when I read that, I saw it as: “The overseer must be (A) above reproach, (B) the husband of one wife, (C) temperate, (D) self-controlled, …”
In other words, I read it as a list of separate qualifications for being an overseer, but it seems like you’re reading it as a list of qualifications for what it means to “be above reproach” (which an overseer must be).
Malachi chapter 2 also contradicts the Torah, in that verse 16 says “‘I hate divorce’ says the LORD God of Israel.” – this despite divorce being specifically allowed in the Torah. Perhaps by the time of Malachi, marital standards for divorce had changed. Malachi is also complaining that Israelite men who had married Issraelite women in their youth were now going out and taking wives from foreign nations (verse 11) – it seems to be the foreignness of these women, not the plurality of the marriage, that Malachi is attacking here.
Well, if by “scripture” you mean to include the Old Testament, then yes. 
(e.g. King David had 4 simultaneous wives, but the only two things he ever did that the LORD was displeased with in the O.T. was killing a man so that he could marry that man’s wife, and taking a direct census of the population.)
But, of course, none of that matters at the time of the early Christians. The New Testament matters – or, rather, as much of the New Testament and other early Christian writings as your average Early Christian had access to, since the New Testament wasn’t really codified until the Council of Nycea in 325 A.D… And the social expectations of those early Christians also matters.
And that’s what I’m wondering about: The social expectations of the early Christians, with respect to polygamy. The New Testament can be read in a way that condemns polygamy universally, but it is not at all clear that that’s the way it was read and understood by the early Christians. I’m looking for something more solid. Are there other writings of the early Christian church that aren’t part of the New Testament, which give a more definitive answer? Are there historical sources outside the Church that comment on their marital behavior?