Whats really going on in the end of NGE with Shinji and Asuka on the beach?

Well, from what I remember and what I've been told, Shinji decides to stop the process that is taking place as everyone's head is popping. He decides that he doesn't want the world to end. It was his will that caused him and Asuka to live. This leaves the potential for society to go on, for people to still exist, although the rest of the population has turned into a pool of LCL.

As for the eva movie, the latest updates can be found at http://eva.trivialbeing.net/ . There are lots of really cool sketches on the site, and Weta (the special effects studio that did King Kong and Lord of the Rings) seems very committed to the project, but it will probably be a very long time until this movie happens. It hasn't even been written yet!