*Do* play the Coke TTW! game...I've won 4 $20 cards already, and I probably win once a week or so, even with only 2 tries per day. If I never win anything else from it, it's a great giveaway.
This 7-11 one? It's pretty lousy, and I have a hard time believing that it's worth your time.
You won't hear back from they. They will send you something in the mail when the promotion is over.