I - Master of Thread.
However now I will say my opinion about Mosaic authorship.
I think that whoever wrote Genesis was probably the same person or it was a group of people intentionally working together. There is a secret in the Torah that shows Genesis was deliberately written as one whole work:
http://www.bereanpublishers.com/a-hidden-torah-secret/
This must mean at the least that whoever wrote Genesis 2 intentionally wrote its words to fit with Genesis 1. They are not two totally independent separate stories by two totally separate authors.
The claim that Genesis 1 and 2 present two separate contradictory accounts of the same creation activities so that they must be made by different writers is actually a broken claim. It relies on demanding a rigid absolutist reading of Genesis 1 and 2 that does not allow any potential confusion by the reader or inaccuracies or even potential nonchronologies.
To demand that they were two different authors, it looks like advocates of that allegation claim that there are contradictions and that BECAUSE there are contradictions, therefore they must have two different writers, as if the same author could not have missed potential significant conflicts in his own lengthy story.
Therefore, I personally reject the claim that Genesis 1 and 2 had two totally different authors.
HOWEVER, was that author a person who exactly personally matched the name and title and biography of Moses we read about in the Torah? I don't know how that could be proven one way or the other especially if the Bible nowhere directly spells that out, other than just
calling this section of the Bible the Torah of Moses.
This is about as direct as we have:
https://en.wikipedia.org/wiki/Mosaic_authorship
Beyond this we don't have a specific direct answer as to how much Moses himself wrote, especially if we mean completely by himself and with no help.