reading restrictions/editing restrictions

I’ve been looking for almost 4 hours and found nothing up-to-date…

What I need to do on my blog is to be able to restrict certain categories (and possibly some posts outside that category once in a while) to be accessible only by registered users (something like premium content).

I found some old incompatible plug-ins that can restrict posts, but nothing for whole category… Do you know of any or do I have to customize my theme/make own plugin with comparing categories and using is_user_logged_in() in soo many places (I’m able to do that, but I would preffer nice working plugin :-))?

Second thing is, I would like to add is to allow certain users to write their own “blog”: to write posts under their own category (nothing more – no multisite required).

Default WP role “author” offers almost everything – problem is, “Author” can write posts to any category – I want to set only one category, where he can submit his posts (different for every author)… Any suggestions?