Pete,
Personally, I'd change the service to Time & Distance (every year or 10k) and upgrade the brakes before remapping. I've got R32 brakes (345mm) waiting to go on mine, Leon Cupra and S3 brakes are the same. They also fit under 17s if you've got them!
I always try to do my cambelt every 40k, but thats because older VW 2.0 16vs threw off their belts at 45k.
Intercoolers and fuel pumps can be changed when you get bored of the power, and I'd leave the rest alone until it breaks.
Oh and I'd get a rolling road test done on it before you start throwing power at it. I found out mine was 50bhp down, so I want those problems fixed first before they cause me other issues.