Rich, read my guide, it's all in there (altho the Mk5 clocks info is out of date 'cos it was only theory then).
Didn't have to move the ECU, altho I will need to pop the dash off to change it (no big deal) and the Mk5 clocks are surprisingly easy to fit, but you need a Mk5 fuel tank to get the gauge to read right.
Heater works fine on all 4 positions. Heat comes out of all 4 vents but the left one is a bit weak (check the fitting guide for an explanation).
/al