Hi, Pete!
In a nutshell, my take on Genesis is that it was a compilation of legends, oral traditions, and later writings of men from a long time ago.
Is it literal? Well, I believe that In The Beginning, God created the (Universe). Beyond that, I have no idea whether the folks mentioned in Genesis actually existed or not.
When asking myself the questions you brought up, I would ask myself what the intentions of these early human authors were. Among my questions to myself are these:
Is there a living Spirit of God that imparts a living truth and revelation into man?(human authors) If so, would not these early authors have had a better view of how reality actually operates? Could not God have imparted enough revelation into them to explain Genesis in terms that are comprehend-able to us today?
Is it important for Genesis to be literal? Ken Ham emphatically says yes but I do not agree with him. After all, according to your O.P. we are assuming that evolution is rational and valid. I see and have no problems with this.
Would the message of the Bible be any less true if none of these people actually existed? Thats a whole topic unto itself, though!
Edited by Phat, : spelling