Touch-screen Gps Navigation (speed Sensor?)

My first post here.

I'm thinking of upgrading the sound system in a 2001 TT Roadster. Here's what I'm considering:

1. Kenwood KVT-815DVD headunit with flip-up touch screen monitor

2. Kenwood KNA-DV4100 DVD GPS

3. KDC-C667 6-disc CD changer

4. MB Quart speakers

I have a few questions:

1. location and wire color of speed sensor?
2. location and color of reverse wire?
3. speaker size?
4. best way to run wires through firewall to the engine and also the trunk area?
5. Is there a subwoofer for factory Bose system? Can I add a sub to the car?

Thank you for all the helps and suggestions!