XQs...About the Nephilim being in Canaan after the Flood, you're totally right about the Noah story being "cut and pasted" into the epic narrative (which assumes that the Nephilim, and the descendents of Cain, were still living into the time of Moses), I go into this subject in depth in the following thread:
http://www.jehovahs-witness.com/10/68224/1.ashx
Noah originally was an agricultural hero, being the discoverer of wine. It was in a later stage that he became the Flood hero.