Is it correct to assume RAF controllers of such devices are always aircrew? Should such controllers be qualified pilots? With offensive action would they gain campaign medals when controlling far from the theatre? Do controllers qualify for flying pay?
In simple terms, yes (it's an aircraft; why wouldn't you have pilots flying it?), yes but not necessarily ones who've undergone the current training pipeline for manned types, no, only when in theatre, and yes, because they're aircrew in a flying-related job.
The Americans have a different stream for RPAS pilots, which I think is a sensible idea. RPAS pilots don't need to have spent hours honing their close formation skills, nor do they need hours and hours of low flying practice. The degree of automation means a lot of raw flying skills aren't required in the same way they are in the cockpit of a fast jet.
However, they need airmanship by the skipload, so it's certainly wise to have some crossover types with extensive manned flying backgrounds in the fleet.
Would you pay future drone-only pilots flying pay? Don't know. If it's still sold as a recruitment and retention measure, then the fact that drone pilots aren't as readily valuable to civilian airlines as manned pilots implies you don't need to pay as much to retain them, so perhaps a smaller rate?
Regarding calling them "controllers," RAF Reapers aren't like little Desert Hawk UAVs etc. They're not flown with a laptop and a little controller, they're flown like proper aircraft; stick, throttle, rudders, a full weapons system, etc etc. The crew are very definitely flying them!