The Red Zone tix were well worth it. Yes, you can go back and forth between GA and RZ. The RZ bar closes just before the show starts. In DC, the band began at 8:30.
Basically, you are escorted into the GA/RZ area before other GA ticket holders so you can get your place up close for the event. Pre-show, it means that one person holds the space while the other one goes to the RZ bar. Honestly, everyone is really cool. That is the beauty of U2 fans. If you are there early, RZ people just hang out together. It was my best U2 experience ever!
Staying in RZ gives better views of the video