What exactly am I getting into?
 

Greetings,

I have my eye on a 2011 base Cayenne with 8sp tiptronic and have several questions:
1. How often is the scheduled maintenance (and typical cost) ?
2. What are the major maintenance items, and intervals (and typical cost) ?
3. Does the base stereo have a seperate amplifier (if so, can it be used with and aftermarket HU) ?
4. What are the dimensions of the speakers ?
5. Can the HU be replaced (I am assuming double-DIN) while retaining steering wheel controls; are there high quality faceplates ?
6. Would replacing the stereo void warranty ?
7. Specific experiences involving aftermarket speakers, HD Radio (big deal for me), backup camera and navi are greatly appreciated.

Thanks in advance.