To answer your questions fuerstma:
1) There is a wiki for the GP2x @
http://wiki.gp2x.org which has basically everything you ever needed to know about the GP2X. I also hit up
www.gp32x.com for their forums, which is a great place to hang around. From the wiki, they link you to a central downloading site which I think is like gp2x.de or something. Eiher way, every application for the GP2X is there.
2) It uses SD cards for storage, so you have to use a card reader. I read that you could use the GP2X as a card reader, but I didn't have any luck. You basically just put stuff on a SD card and it works. I got this really cool front-end for it that offers up a new menu system that's really slick.
3) It uses 2 AA batteries. Battery life on the thing is WAY worse than the Nomad, but then again it doesn't have a bazillion AA's in it. I got probably about 4 hours of total play time on two brand new Energizers. You can get a AC cord for it, but I don't have one.
The emulation on the GP2x isn't perfect, but the Genesis emulation is pretty much dead on. SNES works with some slow down, but if you knock out the sound and bump up the clock speed, it works like a champ.
Right now there are two models available for the GP2X, the F100 and the F200. The F-100 is what I have, and it's the black one with a joystick. The F-200 offers a touch screen and a d-pad instead of the joystick. The joystick is kinda goofy, but I got used to it. I think the F-200 may offer up a little more in the processing power, but I don't know. If you're on the fence about getting one, jump that fence my friend. I am super happy with my purchase.