I found out how to stop the screen turning off - in the same menu that you adjust brightness of the screen there is an "ON/OFF" setting at the very top. This seems to be a "auto time out" screen function as once I turned it off the screen never did it again.
I have managed to pair my phone to the BT (iPhone 4S) - follow Spong's method above but I found I could only find the Bluetooth on my phone when I had the first Bluetooth menu opened, rather than the last.
So my process was:
Info button (Next to TV) -> 4/8 -> 8/8 (Bluetooth) -> First menu item -> Go to phone's Bluetooth pairing and choose My-Car / 1234.
However, the Bluetooth seems pretty lousy quality, I'm not sure where the mic is, but it's got some wild frequencies transmitting to the other person and what I hear isn't great either. My Pioneer headunit in my previous car was far superior.
The steering wheel buttons work though, not sure I could get them working with a headunit.