I heard Chewbaca dies in one of the books, how does that happen?
In the words of the Almighty Billie Wheelz " they dropped a moon on him. He got to be a brother!" Which of course is very close to the truth. During the early stages of the Yuuzhan Vong invasion, while the New Republic Senate pussyfooted around the issue and actually blamed the antagonism of the Yuuzhan Vong on the Jedi, Han Solo, Chewie, and Anakin Solo headed to the planet of Sernpidal to help out. The Yuuzhan Vong used a "device" that would take a planet's moon and smash it against it. So literally, a moon was dropped on Chewie. Solo went into a state of depression afterward and blamed Anakin Solo for Chewie's death (Anakin was flying the Falcon and did not go back for him). Chewie went out like a trooper saving total strangers and defiant until the end.
oh just realized i had another question. drop some science on this whole 'lost twenty' business
The Lost Twenty were Jedi who left the Order voluntarily. They did not do it because they went to the Dark Side but because they were dissatisfied with the Republic Senate and the Jedi's subservience to them. Dooku was one of them. The others have yet to be revealed. We do know that they were all highly respected throughout the galaxy. Check "Jedi Rendezvous" to see how Dooku was highly respected throughout the galaxy.