Selecting specific themes?

Hi,

I'm trying to create a site where users can have the opportunity to use premium themes, if they pay a monthly charge.

Is this possible to have certain ones selected when they pay some kind of subscription, and what would be the best plugin for this? Also, if they could have the chance to do the same with plugins.

Another quickie question. Is it possible to sort the themes into some kind of order, maybe create folders within the themes? This would makle the above easier, but also make it easier for the user, so have a section called 'News' and would show the news-style themes.

Thanks,

Joe