[HummerNewbie]

I have a very similar setup but am using a D1 rather than a Z1, no iPOD and have yet to hook up my rear cam.

1. Where is the best place (inside the vehicle if possible) to tap into the VSS (Speed sensor wire)?

I didn't even bother with this and everything seems to work just great.

2. Where is the best place to tap into the reverse wire?

I plan to run a lead back to the reverse light when I run the video feed for the camera. If this is not the best way someone will chime in.

3. Where is the best place to tap into the parking brake wire?

Don't hook this wire up to the parking brake, just ground it. If you hook it to the parking brake you will have to have it applied to use many of the NAV features. (Applies to AVIC D1, D2, N1 & N2 but check online to see if this bypass still works on the Z1. You might want to check out AVIC411.com)

4. Where is the factory XM module located?
5. Can I reuse the factory XM antenna?

I have not heard a definitive answer on whether or not you can tap into the factory XM antenna.

6. Can I tap into the factory XM wire harness for power, RAP, & ground for the new XM NavTraffic unit?

Wire the new XM tuner into the wiring harness along with the head unit. Which tuner are you using. I went with the GEX-P10XMT.

7. Can the GPS antenna be mounted under one of the roof rails or would that block the signal too much?

Not sure about this but I ran the XM antenna up one a-pillar and the GPS antenna up the other. I have them mounted next to the roof rails on either side. You can not see either of them unless you are above the truck but I do have the marker lights to that helps block them from the front.

8. Where is the best place to mount the rear view camera?
9. Where is the best place to run the camera wiring into the vehicle?

I am going to try mounting one on the inside of the rear window, top/center angled down. May have to play with it a little to find the best spot.

10. Is there a RAP lead near the back of the vehicle to tap into for the camera?

You could wire it into the wiring harness as well then run a lead back with your video feed.

I have yet to truly utilize the XM traffic but I do like it and would have to say from my experience it is worth the couple of bucks a month if they have coverage in your area.