EITS, we do have RNAV for airways flights in all aircraft in the UK but as you realised the kit is often simple and doesn't necessarily have a database. We therefore have to find the waypoint and then manually enter the frequency, radial and distance. Often, the defined VOR is out of range, particulary now filters have been fitted to make the equipment fm immune. All adds to the workload for single pilot IFR.
Regarding QFE, I was taught to set QFE when landing and departing when I learnt to fly, but stopped using it when I started instrument training. I never use it now, always use one of the QNHs or 1013 and can't say I've ever missed it.
Would anyone like to have a go at justifying the use of QFE?