New '08 H2 SUV owner / question on radio

[baldfox]

Hi guys, first off wanted to say hi to everyone. I just collected my first hummer yesterday (2008 black SUV). Am really pleased with it, 18km on the clock, so in great condition. Been looking through all the forums etc, but just one question re the headunit (it's standard but non nav) it's got bluetooth button/connect to phone on the steering wheel ? does that mean there's bluetooth on the radio or an OPTION to have it if i purchase the required module ?! I can't find for the life of me how to set it up to speak to the phone if it does have (car didnt have the instruction book).

I fancy swapping out the headunit anyway for a later model GM nav unit if it would fit. So far i keep seeing cheap ones on ebay that look like they come from the far east. Anyone know the official maker of these or a good factory unit that I could get that has all the goodies on it ? I'd like to keep the rear camera (integrates to the mirror) and the rear roof DVD player, so not sure if these are simple connections or not?

if they are simple, then maybe I'll swap it out for one of those new pioneer headunits, They even accept hdmi in, so could get a raspberry pi in there and have XBMC in the rig. Not sure.

Hope everyone is well, thanks.