As a general statement with regards to all 4 of your questions I would answer with an acronym.
"NETS"
Not Essential To Salvation
Those are not the important questions....those could/ would be what Brigham Young called "decoys". (the adversary is doing some hunting)
Once a person knows that Joseph Smith was a true prophet of God and that the Book of Mormon is real....by having God reveal that to them...it is pretty easy to ignore the philosophies of men.
but here is a little bit more detail I guess:
1. DNA - First of all it is in the intro...therefore it really doesn't fall into the same category as the Book of Mormon...the intro was not on the golden plates...
In any case I did read something that satisfied me on the subject long ago, I really don't even know where I read it or what it was...it really matters that little to me....I mean when God revealed to me that the Book of Mormon is true and that it is the word of God by having the words on the page practically glowing as the Spirit came over me and testified to me that it is true....I simply can weigh my evidence and witness from God vs. some men who are most likely trying to discredit the church...for me it isn't even a contest.
2. Book of Abraham - I've read a tiny bit from Hugh Nibley on the subject - I don't know enough to say too much about it. But again...since God showed me which Church to join (by a vision) and other powerful spiritual experiences and the Pearl of Great Price is one of the Standard works of the Church ...and that I feel the spirit when I read the Book of Abraham...I judge that it is a holy book and the word of God.
3. multiple wives - pretty much this comes down to living by the spirit...living by modern revelation...Abraham also had mulitple wives...Abraham also was commanded to offer his son as a sacrifice...the thing is, is that the things that God commands will ONLY be able to be discerned if a person receives revelation from Him. In fact one of the definitions of an "Abrahamic sacrifice" is that it will NOT make sense.
4. wording in the Book of Mormon - For the most part the Book of Mormon is NOT written in that type of language. But Joseph was actually very familiar with the Bible and its language wasn't he? I think it is great that parts of the Book of Mormon are similar in that style of writing to the Bible. In fact it is almost as if it is the 2nd witness spoken of in the New Testament....(In the mouth of 2 or 3 witnesses shall every word be established)...the subtitle of the Book of Mormon btw is called "Another Testament of Jesus Christ". (So to be plain actually what I mean by that is that it IS another testament of Jesus Christ! it is a 2nd witness....)
There will also be another witness when the lost tribes bring their records and they are also identical....will you believe then?...on what basis would you think you would believe a 3rd witness if you don't believe the 2nd witness?)
Luke 16:29 Abraham saith unto him, They have Moses and the prophets; let them hear them.
30 And he said, Nay, father Abraham: but if one went unto them from the dead, they will repent.
31 And he said unto him, If they hear not Moses and the prophets, neither will they be persuaded, though one rose from the dead.
There are already plenty of witnesses if a person desires to know...There are living prophets and apostles (if a person desires to be spoken to). There is the Book of Mormon (if a person wants to read it). There is prayer (if a person wants to feel a personal witness from the spirit from God)...there are the missionaries (if a person has sincere questions and wants a personal touch....to have a special invitation to join God's kingdom)....
So even if one rose from the dead...who would believe? If records came from the lost tribes...who will believe?...
Luke 16 makes it pretty clear that the problem isn't that true information is not being GIVEN! the problem is that the information is not being RECEIVED! ....
but Jesus says...His sheep hear His voice...so ...let him who hath ears to hear, hear.