I'd like to learn about Office 365 and how it's paid for.
Is this the next version after Office 2010?
It's an update of BPOS, moving from Exchange, Communications and SharePoint Servers 2007 to Exchange, Lync and SharePoint 2010 with a few improvements.
The client software for end users is still Office, along with the new Office Web Apps. The subscription costs include Office (although there are subscriptions for kiosk workers that only include the web apps, IIRC).
It's licensed per-user.
It's not the "Next" version of Office, it's the "Cloud" version. It's akin to Google Docs, where you edit everything online instead of on your computer.
There are three major silos of licensing for Office 365: Small Businesses, Enterprise, Academic.
The small business plan (P1 - $6/user/month) has largely been ignored in favor of the Enterprise plans (even by small 1-3 user businesses). This is because Microsoft arbitrarily handcuffed a bunch of major features that they figured small businesses wouldn't need. We've moved 3 customers onto P1 and had to later move two of those firms back off because key features they needed were locked down. We've adopted a policy of never selling the Small business plan since then.
The enterprise plan ranges from $2 - $22/per user/month depending upon the features you are looking for. Here are some useful guides:
An overview of all general pricing info: http://www.office365advisors.com/pricing/
An deeper dive into what the different mailserver features are with different plans: http://www.office365advisors.com/exchange-licensing/
Lastly, the Academic plans are licensed completely differently where students are typically free if staff pay.