Requesting advice on the Benko Gambit

Until recently, I have played the Nimzo-Indian against 1. d4 as black, and I have never felt comfortable doing so.  Due to this, I have decided to select a new opening to combat 1. d4 and I have settled upon the Benko Gambit.

That being said, I have a few questions to ask of the community.

1. It seems that there are a variety of systems in which White accepts the b5 pawn but declines the a6 pawn; which of these are the most common and how should I play against them?

2. When White does accept both the b5 and the a6 pawns, and thus accepting the gambit, I know the King Walk and the Fienchetto Variation; are there any other variations I should be aware of?

Thanks in advance for all of your help!

My advice would be to join a group dedicated to the Benko Gambit.  To wit...