I am going to offer you advice about how to run an online community for an alumni association: simplify. Complexity is intoxicating, but simplicity is useful.
I set up an alumni association website, isu-usa.org, to have ISU alumni share their contact info with each other. Our mother institution, ISU, had set up a site in 2007 to do this, but... let's say... that... it is not the most useful... thing. (See that? Restraint. /twitch)
My initial take on setting up isu-usa.org profiles was to request the same data that the ISU site requested. Add to that a request from an alumna to also share our educational backgrounds, and ISU*USA profiles collected data from 42 fields. (Fields such as first name, last name, email address, etc.)