Hi Vishnu,
These things would require custom development. The first item could possibly be done by implementing a custom user registered handler
http://www.mojoportal.com/user-registered-event-handlers.aspx
I can't really think of a good way to implement multiple profiles per user, it also seems like a strange use case, their is naturally a 1 to 1 correspondence between users and user profiles.
Hope it helps,
Joe