This is just third question again:

I'm not sure here. Look at this paper, for example, in which the author suggests a few points of differences between the two theories and some practicality issues. There doesn't seem to be much concern over what's "fundamental," only over which model is more useful and in which situations this is true.

Edit: Actually, now I'm confused. I'm going to leave the text above, but I'm not sure I agree with it. I'll reply when (if?) I figure this out.