Best Themes / Plugins / etc for Online and Offline membership

I’ve purchased WPMUDev for a specific task, which is the running of a specific kind of Membership site.

The site will have a mix of members; Silver, Gold, Platinum type of levels.

Silver will be ‘Online only’. Gold will be Online & Offline-Geographic based, and Platinum will be Gold plus other benefits, and will possibly include a wider Geographic area.

So there are levels and also geographic sets.

There will be some Digital downloads, some released as soon as a member joins, some on a drip-feed, and other content generated on a weekly / monthly basis available to all members and then archived.

There will be monthly meetings for the Gold and Platinum levels, and probably also bi-monthly webinars, and other regular and ad-hoc web-meetings (for which I anticipate using the Chat plugin).

There will be local Clubs and a National club.

There will be a Joining Fee and then Monthly fees.

There will be Facebook integration and a/some FB page/s, but I want to keep the chat OFF FB and IN the club, for privacy and archiving reasons.

I will need the ability for different sets of members to use chat rooms (from 2 to 50 members, probably); some of which would be set up by the Club and others able to be set up ad-hoc by members, which would be private to just those members but conversations archived and accessible by Admin.

So, I’m looking for a recommended mix of Theme(s?) and Plugins to accomplish this, or at least to start with, understanding that I can add other Plugins for other functions as I go.

I would also like to understand more about BuddyPress as opposed to WordPress, and if the Themes / Plugins are different for BP?

I have multiple Domain names, and am thinking I might link several sites for related subjects.

Am not sure if I need a multi-site or if the Social elements of this indicates a BP type site (from what I have read so far about BP, although, that isn’t a lot.)

Thanks for your help. (I did post a version of this Q last week but it had some slightly commercial info so the thread was deleted.)