BuddyPress.org

(1) and (2) don’t require BuddyPress at all. For (2) you can use a custom post taxonomy or a custom post type (or plain old categories) to distinguish your own articles from your users’ content.

As for (3), BuddyPress doesn’t have a rating system built in. There are a lot of WordPress rating plugins, and I’m sure one of them could be adapted to work with BP.