make sure its a 1.8t and not a 2.0 gti 
+1
Also the turbo should kick in around 2-2.5k RPM and hold nice up to around 4-4.5 and slowly die off.
Look at the wishbone arm on the pass side look for what looks like oil spillage could indicate a leaking steering rack = new one require not cheap as I just found out lol
There is a button in the dash called ASR i think if you press it an orange light should light up on the dash. Leave the light off and try and floor it from a stand still, that light should light up on the dash and flash and power should die, this will indicate your traction control works
Try the key in all the locks its common that the key don't work in the boot, mine is like this.
Try the rear washer jet again commonly goes and leak water down the rear pass C piller and leaks fluid into the car, a right pain in the arse to fix or you can de-wiper like me
Other things then are usual checks on a car, oil, make sure there is no mayo type stuff in it, Service history, when was the brake fluid last changed, etc etc, do the gearbox feel solid?
Keep us posted
