I think most of your questions will be answered by these threads:

http://www.dbasupport.com/forums/sho...threadid=19196
http://www.dbasupport.com/forums/sho...threadid=19824
http://www.dbasupport.com/forums/sho...threadid=19712

The first one gives an INDEX BY TABLE and a VARRAY example.

Good luck.