hiya.
Nikki's powers kinda suck, yeah =) Just a schizo. Not really a super power. It would be cool if she could like, split into 2 people.
Nopes, I don't think he isn't Syler either. He seems to be a bad guy, but I don't think he is. He does have a lot of power though. I believe there's still a higher power above him.
Yes, I think Syler eats brains or something. I think there's something in the brain where the superpowers lie, and probably extracts them for his own use. Notice how he had multiple powers when Cop guy and white detective was chasing him?