For info on the set times for each band, you can get that the day of the show. Meet and Greet times will be sent out via Twitter by bands and will be posted around the venues. This may change day-to-day.
If you don't have the Official Rockstar Energy Mayhem Festival iPhone app, you can download it from iTunes on both your computer or iPhone. It's totally FREE and something really cool to have, especially when you're at the show.