why is kal pen doing that hipster voice..?

His voice and the dialogue ruined it for me. I didn't make it through his first scene. Awful!!!

I was wondering when he turned into Nicholas Cage

I don't know this guy, but I'm assuming he doesn't actually talk this way. His character was almost certainly intended to be an unlikable piece of smug city garbage. This was likely so that his posse being killed would not be something to lament in the film, but instead something you pray for (with the exception of the assistant who falls for Colleen). I think it was intentional that the script had him saying what was possibly the stupidest set of lines in any movie ever made (the part where he "introspectively" makes an analogy between himself and the PC vs. Mac rivalry which itself is incredibly stupid and lauded by hipsters for some reason). As he slowly delivered that part, and I could see where he was going, I was begging "Please don't say what I think you're about to say." I found it so immensely stupid that I was actually angry with the filmmakers momentarily, but then I realized that this was the greatest way to cement the character as the ultimate douche.