Yes

No and neither does the most ardent fundamentalist. The tradition is that Moses wrote the first 5 books, under the inspiration of God, and the others were written by various authors also under the inspiration of God.

Since we don't have the original manuscripts, none of us know.
Biblical literalists state that the originals were without error even though there are errors in the oldest known Hebrew manuscripts. From my point of view that belief is merely an assumption without physical evidence.

There are errors in the oldest manuscripts...the number of Solomon's stables...rabbits chewing cud...etc. There are seeming contradictions in the Old and New Testament that cannot be resolved using a literalist stance. Jesus' actions occurring in one order in Matthew, and a different order in Luke. You can say that it is because the accounts are from different witnesses but that explanation makes it an error in the original manuscript. If God wrote the Bible, why would He allow these contradictions?
BTW: I accept that there may be different witness accounts of Jesus in the Bible. It makes the Bible accounts more realistic, in my opinion. However, acceptance of contradictions in the original manuscript means that we must accept that the Bible is not literally inerrant.