Question1: Do you think users should be able to choose their own skins that they view?
I'm thinking no, because the person running the album might want it to have a particular look and feel, depending on what he's doing with it.
Question2: Should users be able to choose skins for each of their categories?
I'm thinking yes, because some categories might be special (Christmas one, for example). But I'm also thinking no, because the skin changing from page-to-page might be a little annoying to users.