What dirigible said.
and,
RPS - is primarily made for co-op mutiplayer gameplay, where the other Source Hunter is controlled by someone else. You should try it, its great fun and substantially alters how the game plays.
I dont mind it happening when im playing solo because it increases the feel of me playing with two different characters.
Star Stones - you will find plenty. They are relatively hard to miss once you find the first few ones and get familiar with the general gist of it.
