I see that many people here suspect Nick to be a "double agent" on the basis that 1) he was a close friend of Vinny, 2) his room was left untouched during the attack in episode 5. But these are the only clues. I don't agree that he 'acts suspicious' or anything like that. He is just a calm and collected guy. If he was a double agent working with Vinny (who obviously tries to destroy the DIKs out of revenge), Vinny wouldn't omit his room in order not to arouse suspicions. I think Vinny, when he attacked the DIK mansion, didn't touch Nick's room only because of their past friendship. From various conversations with Nick throughout the game we learn that he was never directly involved in the conflict with Vinny. Vinny left because of conflict with Tommy and, maybe, Rusty. It's very probable that while he holds a grudge against the DIKs as a fraternity, he doesn't hate Nick specifically.
Also, regarding the camera in janitor's closet/Derek's room, it's pretty obvious that Vinny is the one in control. He used a picture taken from there as part of what he anonymously sent to Dawe and Chad at the end of episode 2. His goal is to destroy the DIKs and one of the ways to do that is to constantly provoke further conflict between them and the jocks.