Best runner: Hell no. AP wins that title hands-down. He's probably top 5, though.
Best pass-catcher: Probably. Forte would be in the conversation as well, but it's hard to pick against Charles since the offense revolves more around the short pass than Chicago's does.
Best in open field: Again, difficult to pick against him, assuming we're only talking about feature backs (otherwise, Darren Sproles would probably take the crown here).
Fastest: Yes, although one could make a case for Chris Johnson here as well.
Overall: I don't really see how you can't put Charles at #1. A year or two ago it might have been different, considering AP was actually healthy back then, but now, Charles seems like the clear-cut #1 to me.