There is no question as to who wrote Genesis. “The book of the law of Moses” and similar references to the first five books of the Bible, of which Genesis is one, are to be found often from the time of Moses’ successor, Joshua, onward. In fact, there are some 200 references to Moses in 27 of the later Bible books. Moses’ writership has never been questioned by the Jews.
Yes there is. There are at least FOUR different authors for Genesis (and the other four books too, I believe) alone. These are called J, E, P, and D, if I remember correctly. After Jehovah, Elohim, Priestly and Deutoronomy.
I'll dig up a nice documentary on who wrote the bible for you to watch, you'll have to wait until this evening (my time) before I can link you to it though.
I hunt for the truth