I feel like I should be making a post here about EoE, but I don’t know what to say other than "I finished it." It was better than the original ending, but still really confusing. (If anyone wants to try to explain it to me, go ahead.) I got lost somewhere around the point when Rei entered Lilith.
In the constructive impact, all of humanity would evolve to the point of no emotions and as one single entity. To get this all of the Angels which are like trails to prove man to be worthy of becoming a being like a god, had to be destroyed before coming in contact with Adam. Then a artifical Angel like EVA could start it. This was Gendo’s dream because he would be reunited with Yui. He had to use Rei though because she was cloned from part Angel and part human (Yui’s DNA) so she could start it for Gendo. However she would turn on him and not take him inside of Lilith. Unlike the simple plan of just starting it a crucifixed EVA piloted by a pilot who has moved througha different set of trails. (Forgot the name, religious though)
Then the other: If any of the angel’s come in contact with Adam it will start a reaction that will destroy mankind.
A second possible outcome of the Constructive Impact: If the pilot fails to complete his trails mankind will not evolve and it continue to live as it was before the 3rd Impact was started.
Fujin I am not completely sure on this theory: All who died in an attempt to reach the 3rd impact will be reborn. Asuka says something very interesting at the end. The last sentence tells the rest of the story.
Also, The EVA Sage (http://www.geocities.com/Tokyo/Fuji/3082/) (dont let the geocities hosting scare you) is an absolutely fantastic site that has an enormous amount of text discussing the meanings behind everything in the series/movie.