1) Possibly. I just thought it would be significant if one island kept all the evil at bay and the other island was the counterpart to the first. Like EIG and Jacob.

2) "Dogma"? I didn't see it that way. I don't think he'd undo all of existence - just that of the Losties. What would happen to the rest of the world still isn't clear to me, but I guess EIG would rule it and it would suck.

3) Alternative universe parallel. Echoes the idea that you can't correct the course of time - things happen at different times in different universes but things that were supposed to happen happen.

4) No comment

5) Seems to be nothing more than a plot point - blow to the head caused the aphasia (sp?), can't speak english, going to make things difficult in the final episodes.