Bosons and fermions are all that is out there...at least in the standard model, anyway. There are all sorts of other theories out there with their own zoo of particles that have yet to be discovered, however. Who knows what else exists.
The only allowed spins in quantum mechanics are of integer or half-integer values.
String theory does not unify the four forces. Superstring theory (string theory with supersymmetry) may, however. It remains to be seen.
I'm not sure what you mean by "what are all the 'actors' in the SUSY world." Care to elaborate on the question? Read
this paper and just skip over the math to get a rough idea of what you'd be dealing with. Perhaps it will help answer some questions.