After posting the entry regarding the problems I'm having with Community Server, what I had written had a moment to sink in and it hit me... I wonder if having two different connection strings might be the cause of the user creation problem. Sure enough, I just created a user and it worked without a hitch. Go figure.
Now just need figure out how to get the search to reindex and find a solution for how to use all that CS has to offer while still maintaining my search indexed links.