Some EA113 KO4 engines (ED30, S3 etc) had weak valve springs and there was a VW TSB for it, so tell your mechanic to check the coloured bands on the springs. If they are white and yellow, they need replacing for the uprated ones.
Burned out valves doesn't normally happen on standard cars though. Weird.
Yep, do all of that whilst you're there. Are you getting a brand new head, or a used one? If the latter, make sure you clean out the intake valves / ports.