Are we Predestined?

Are humans good or evil? Do we have free will or are we predestined? Is there an excuse or justification for our actions? What and why do we act upon?
These questions are very common. I guess we could even call the cliches, still the way in which we react to them is unique and personal for each individual. Even Vonnegut has these doubts and relates his book to these questions. He is constantly highlighting human cruelty and how we are always making so many wrongdoings. he even highlights our perversion at one point. ´"That's not what you want, for Christs sake." He told Billy."What you wants in the back."´ Here the bookstore salesman is referring to the back part of the store where all the porn is. He is amazed and actually laughs at Billy when he realizes hes not interested in porn but all he wants to do is buy a Kilgore Trout book, their display "garbage".
Vonnegut also indirectly relates his book to human dignity. He kind of tells people that the only way to justify such horrible human behaviors is to think that things happen the way they do because it is meant to be that way. By looking at things this way, the Tralfamadorian way, he gets to calm some of his uncertainties and some of the things that probably haunted him after war. He stops taking all those actions personally and stops questioning them and just accepts them.
Vonnegut reaches an interior peace, or at least gets close to it because he takes away human guilt and human will. It is no longer our decision what we do but we just end up doing what we are meant to do. This theory takes away our blame because it means that it wasn't us who CHOSE to do all those bad things, we just had to do it so that things would work out. We did not have the bad intentions and we did not wish anybody evil. This is also taking away the reason for why we decided to act in one way or another because we just did it so that the future could complete itself. However, the fact that Billy/ Vonnegut found a way to clam himself down doesn't mean I found a possible satisfactory answer, I still wonder about these questions as they pop into my mind every once in a while.