Technically, Ben started a PF for us last year and Cliffy started at C, but Ben often ended up guarding the more physical man, usually the C. It's hard to call him one or the other though. He went to the all-star game as a C after all. It's not a stupid question, don't worry. Many people don't know how to classify him.
I think at this point in his career, though, Cambell is better suited coming off the bench....either that or give him very limited minutes from a starter's perspective...
I'd hope Okur gets the starting spot this year. He has shown signs of being a special player, and I think deserves the starting spot.