Account Restrictions for Authors

Hi, been battling with WPMU and thinking i might need just WP. So for my blog site, I’ll be the admin. I will set up accounts for my friends when necessary. So John will write entries and he’ll need to select the “John’s Blog Entries” category. Mike will write entries and he’ll need to select the “Mike’s Words of Wisdom” category. I want to do it this way so that people can click on Mike or John’s categories to see all of their entries specifically.

My questions are this:

– Can I set up WP 2.1 so that a specific author can only post in a specific category?
– Can “author” accounts delete postings? I want them to be able to write entries, but have the admin approve them and edit them. The “authors” should be able to edit but not delete anything. Is this possible?

Thanks so much!
Cent