I'd say start Maroney and Betts at RB. If there's a lot of scoring in the Indy/NE game, you probably want to start all of their offensive players you can. You're right that your options aren't TOO good. Westbrook practiced today, and Bell is splitting touches with Pierre Thomas and Reggie Bush. But you're right, if Westbrook does sit out, then go with Maroney and McCoy.
For your flex, I say go with Collie. That game (IND vs NE) ill probably be a shootout, so everybody in the Indy passing attack benefits.
Take a look at my RB dilemma: viewtopic.php?t=460525