Check for swarf in the power steering res. Clonking from the top mounts, and check the condition of the rear trailing arm bushes. Other than that there's not really a lot that goes wrong with them, and they're considerably more reliable than the Mk3.

Good engine, plenty of poke and they can take the miles well (Mine's on 138K on original clutch and still drives mint)

I did my cambelt at 125K, no real reason to do it sooner.

I get around 35mpg with spirited driving, mid 40s on a long drive. 50+mpg is perfectly possible if you're on an economy mission.

Be wary of a remap - done wrong it will eat the clutch/DMF. They don't appreciate too much torque at low rpm, so the map needs to take that into account. Speak to the tuner first and see if they already know that. if they don't - walk away.