Explain NGE to a newb

So I caught the last 40 minutes or so of "Neon Genesis Evangelion Final" and am totally confused.

Why is Shinji strangling Asuka at the end?

Did anyone else think this was one big pretentious trying-to-be-art mindfuck rather than having some real underlying plot or message for the viewer to understand?

After reading about the creator of the series suffering from depression, the whole film really seemed like the expression of one crazy guy's screwed up mind. I'm sure it's meaningful to him, but to regular sane people it's meaningless.

>>4

So if the movie-version with all the episodes joined together had the ending changed, what was the difference from the original final episodes that aired?

Also that's pretty interesting, as they seemed to have a much different style than the rest of the film. Now I know why.