I was going to write a longer detailed post about this, but I gave up on it because I'm still trying to grasp all this myself. So here's the summarized version...
Actually... this "summary" too turned out to be longer than I thought it would, and is probably more than you expected. Also, even though I might come across like I'm totally sure of what I'm saying here, I'm really just thinking out loud, so please take whatever's useful and throw out what doesn't make any sense.
Errr... it seems I can't fit everything into one single post...
(continued below...)