Is it possible to do some things with voice command while driving that you can't do on the touch screen (due to factory lockout)? Also, is the voice command function activated with a PTT (Push to talk) button or is it "always listening?"

1. yes it is
2. you set it to ptt or always on, not sure if always on works or not..

Yes the Voice Controlling kit is very nice. If you don't do the bypass, which takes only 30 seconds to do with a Circuit Tracing pen (see the other post about bypassing), then the Voice Control remote allows you to access MANY functions you can't do without the bypass. You can request additional waypoints like Resturants, modify your route, cancel the route, select any address from your address book, get almost any POI, it's very handy.

With the bypass, you can do anything from the screen...

^^^
can't find your other post about bypassing this.

more info please - this sounds right up my alley.

BlackEJ, if you have the AVIC-N3, Look here for the mod and pictures:
http://avic411.com/forum/viewtopic.php?t=80

The N3 is simple as flipping a switch and grounding a wire.

The N2 required some soldering or the use of a circuit trace pen, plus grounding a wire.

Hope that helps!

Mike