If you want to download custom maps, go to rtcwfiles.com
As for connecting, maybe you tried when the master server was down? Try connecting through All-seeing eye and you'll have more luck.
AirGibson, if you can round up 6 or 7, I can probably get Zer0 to give you guys a scrim so you can start getting a feel for comp. Plus it'd be fun scrimming some more t2'ers, since Cookie's a bastard and only plays Halo now.