How do I manage a user profile section that only the admin can edit/view?

I'm trying to create a user profile that has 3 parts: (A) user must fill out to register (B) user fills out later, and (C) internal control - every user has these fields but only the admin can edit/view - e.g user's rating. What modules should I use to do this? Wis the best way to manage (C)? Right now I have followed a combination of Michelle's docs and Fago's handbook, but can't get C to work.