User Role Configuration with BuddyPress

I have a somewhat complicated question regarding how to configure various user types for my site.

There are, in theory, three different types of users:

1. Regular site users, who would log in using third-party social network identities (Facebook, Twitter, LinkedIn, etc) via a social login plugin-- if you would be so kind as to recommend one, I'd be grateful. There are a lot of options and I'm not sure which is best suited for what I'm doing.

2. Site Partners (Pro-site users). There are several tiers of Partner membership, ranging from a no-frills free tier to several paid levels, however ALL Partner accounts must be MANUALLY APPROVED by a company Administrator prior to account activation, without exception. How do I set these accounts to "Pending", prior their authorization by an Administrator?

3. Profiles. Once authorized, Site Partners are able to create their site and also are able to create Profiles on our Network for an additional, per-Profile fee (invoiced monthly). Regular Users must be able to comment, post content to, and "follow" these Profiles, but CAN NOT CREATE Profiles themselves. One Regular User will be designated by the Site Partner as the moderator/admin of each Profile at the time the Profile is created, and should be able to reassign these duties to another Regular User without the authorization of the Site Partner.