Should really read: http://www.scribd.com/doc/25138962/Piracy-in-the-Greater-Gulf-of-Aden (esp. the section about what Somali piracy is like currently)
What ports are being used?
Pirate bases: Eyl, Haradhere, Garad, Ras Alula and Hobyo. Harvard Paper on Somali Piracy. Dec. 2009
How many ships there?
Details on how they hold ships offshore.
Sometimes they will contract out the holding of ransomed ships to other pirate groups. Link