Community Blog Site

I am starting out on a project to build a network of blogs. Here are a few of the challenges. If you have any ideas on how to get started I would appreciate them.

1. There will eventually be 4000 blogs, each belonging to a specific group of people.
2. There will be two different types of blog. One blog is edited by one person, the other blog is edited by multiple people, they share the blog but can only edit their own content.
3. The blogs need to be indexed by type, province, and city. There also needs to be several ways to sort a search the blogs, by name, province, etc.
4. Each blog, is actually less a blog and more of a mini website displaying pertinent information (i.e. meeting times, contact info, upcoming events, etc.) Somehow I need to have a bunch of mini sites where at least those three sections appear on each.

That's a good start. I'm not looking for total solutions obviously... but if you have any hints, tips, or modules that might get me going in the right direction let me know.

Thanks.

Chris