Setting up a multisite ehh site, with various features and plugins – clueless!

Hi! I have come to realize that my ambitions are far greater than my skills, and I would be so greatful if someone would take the time to shed some light on my issues for me:

What I am wanting to do is create a magazine style website with various articles, and in addition a bulletin board/forum, tools, market place/classifieds and the possibility for the users to create a simple homepage based on pre-defined templates, and a blog. I would like there to be only two access levels (except probably an additional one for moderators?):

unregistered users would get access to the articles, reading (but not posting) the forums and reading (but not posting) the market place.

The registered users would get access to all the features (no subscriptions) upon registration, including creating their own homepage and a blog. In a perfect world I would be able to show a feed of new blogposts from the users on the main site (in addition to the articles).

My first question would be: Is this doable at all?

At this point I have installed wordpress multisite – I assumed that’s what I needed if wanting to let users create homepages and blogs, but I could be wrong of course. I have also installed buddypress, and a whole bunch of WPMU plugins (and the dashboard), such as the classifieds and Membership Premium.