Multisite design with common main page

I am attempting to create a site with multiple subdomain blogs, but I keep running into stumbling blocks in the design and I’m having trouble figuring out my best plan of attack. Here is what I’m trying to do (incidentally, it’s for a high school’s website):

1. One main page with links in the nav to 3 sub-blogs + 1 static page (I’ve pretty well solved this problem by hardcoding, bit of a pain when trying to include child pages but I think I have it).

2. On the main page, I need a blog that will selectively show posts from the sub-blogs, whether it’s by filtering using categories or tags (this seems to be the only potentially likely solution).

3. On the sub-blog pages, I need to be able to selectively allow posts to be viewed on the main page when they’re created – again, filtering using categories or tags. As well, I’d like to restrict the tags/categories someone can use.

4. On the sub-blog pages, I want the header logo to link to the main blog page, not the sub-blog’s main page.

5. Not showing up as one of the 3 sub-blog pages, I’d additionally like to be able to create some extra sub-blogs that can be linked to from sub-blogs or static pages.

Just to give an example so you know what I’m talking about, I would like the nav to contain links to blogs for Parents, Students, Teachers (password protected) and a static About page. Under the Parents and Students sub-blogs I’d like to be able to link to a static page for the Guidance department. From the Guidance department page, I’d like to be able to link to a sub-blog that contains information about Student Employment that can be regularly updated by the Guidance department.

6. I’d also like to be able to carry over widget info from one blog to the next. For example, the Events Calendar will contain information regarding events for everyone, not just one of the sub-blogs or the main blog page. I have a feeling this is unlikely though, so if not I may have to resort to a Calendar page.

I appreciate any help I can get. I’ve installed a few plugins that I thought might help, such as More Privacy Options, Restrict Categories, and WordPress MU Sitewide Tags Pages, but I feel like I’m just going in circles.

brad