Pointing me in the right direction

Hello -

Thanks everyone for their response and input on these sites. Honestly, I'm a beginner and everyone's experience is definitely great to be around.

I was hoping if you could point me in the right direction. I have a request to make a site that would feature two very different futures:
- commenting and 'rooms': the site is about events; the events have a post page. if conversation around that event becomes active enough, the site administer creates a 'room' that behaves like a private forum and informs all of the conversants that the room is open. Acces to that room can be posted on page much like regular navigation
- subdomains for writers: so followers of the site range from beginners to very experience, what I was hoping was for some way to give them notable posting and contribution ability so they could create posts and articles that would show up on the site and also on their own smaller site associated with the larger site. The subdomain would just be their stuff (in the overall site's look and feel) but the larger site would display their articles as well as the events and posts of other contributors.

I really appreciate anyone's insight into possible recipes for this - many many thanks.

Philip