BuddyPress.org

I guess you would need to elaborate on what your “custom info for alerts and updates” are going to be.

The rest of them can be remedied with what you said.

But, the cool thing about BuddyPress is you can enable/disable various components, so say you don’t need groups or blogs or friends, you can disable that in the BP admin area.

It sounds like you really only need profiles, and perhaps the wire, or maybe groups, to faciliate the alert service. The bpEvents plugin by Erwin Gerrits can help you for events as well.

There’s also a Facebook Connect plugin available and a Twitter plugin in the works.

Hope that helps in some way!