bernyfly you got it!
The assessments are the most important part. Of the two, group-ex and computer, the group ones are critical. Lots of people are chopped after a poor group ex. I read the section on group work from 'get a head for the sky' interview prep book and it went like clockwork. Only three from the other group got through including the timekeeper who had also read the book.
On the computer, don't forget the primary task - flying the cross-hairs! Guys were saying they were getting the math and shapes but the cross was out of sight... not so good.