The clutch isn't as much of a problem as the dual mass wheels that are fitted to these tbh, a tell tale sign is if you can feel a pulsing or vibration through the clutch pedal when lightly depressed or a rattle when you turn the engine off.

As for the auxiliary belt, they suffered with the tensioners going weak and causing a loud rattle at idle, i would suggest changing the tensioner at the same time as the belt tbh, along with the front crank pulley, they have a damper in them which also go weak.

Don't know much about remapping diesels tbh but i would be a little wary at that mileage if its on its original turbo, my father in law had his vw transporter remapped at a similar mileage and the turbo failed quite soon after.

Hope that helps, Karl