A Few Questions About Car Audio USB/MP3

My Equipment
AVH-P4000 DVD
Seagate 250gb HD
ZUNE 16HD

I have my portable hard drive connected via USB to my head unit and it works fine....for audio.

Question #1 - Is video playback allowed through USB?

I know that you can connect a zune into a HU's AV connections.

Question #2 - Is there an adapter and/or unit that allows you to control a zune through a touchscreen head unit like you can do with ipods?

Zunes have optional docks, in which you can connect your device to a/v inputs/hd and charge them with USB at the same time. While this doesn't help me with unit integration, they also come with a remote control.

Question #3 - How difficult would it be to remove the IR sensor from the dock and move it and/or blast it so I can use the remote without direct line of sight?

Thanks to anyone who can help with valid information.