Airport/U-Verse Configuration

Okay, I've spent way more hours than I'd like to admit trying to properly set up my network. Here's what I'm trying to do. I've got a 3801HGV Residential Gateway, an Airport Extreme (MC340LL/A), and an Apple TV. I just got a new Macbook Air and I'd like to be able to remotely access the external hard drives I've connected to the AE. I have the ethernet properly connected but what I have struggled with is the right combination of settings in Airport Uitilty. The problem is that I would like to be able to use AirPlay via the Apple TV but I am only able to get that to work if I bridge the Airport to the RG. However, Back to my Mac only works if I'm set up with the DHCP-NAT router mode and then AirPlay worn't work. I've tried opening the proper ports for Airplay but still can't see it. I've tried static IPs, DHCP reservations, etc but honestly don't truly understand what that all means. Can someone please help a networking noob? Thank you!