FINAL TRAILER: "X-Men: Days of Future Past"

The third and final trailer for X-Men: Days of Future Past (May 23rd) is here, and it's a doozy all right. Third trailers are usually rehashes of other clips they've already shown, but this one's different- it might even show too much of what's happening. But I have a question- why is the young Charles Xavier walking around in this movie? We did see him get shot and paralyzed in First Class, right? I'd also like to know why young Beast looks like Nicholas Hoult again- he's not supposed to be able to change his shape back and forth like Mystique is he?