Would like some advice on plugins for free and paid membership, and pay per post plugins

I am new to WordPress Multi-site, so please forgive my newb question.

This is what I am looking for and would like some advice on plugins.

2 membership types:

1. Free Subscriber Account

2. Paid membership – annual basis – through PayPal

Free Subscriber Account

1. Can comment on articles/posts – per blog

Paid Membership

1. Allows commenting installation-wide (all blogs) – including main site

2. Gives multi-site subdomain blog

3. Allows unlimited free posting to their own blog, and pay per post to main blog (moderated). No access to other “sub” blogs

4. Can install own themes

5. Can activate/deactivate most plugins, but cannot install plugins. I would like them to not have access to deactivate certain plugins (like the Global Footer Content).

I would like PayPal integration. So, a user clicks on a “Buy Now” button, goes to paypal, pays, and when they return, they are presented with the automated blog creation wizard.

I can’t think of anything else right now, but will post more later if I come up with anything.

Any help would be greatly appreciated.

P.S. I already installed the Global Footer Content plugin. How would I go about keeping it on all the sub blogs, but remove from the main blog?