Maybe just another comment on cycle paths and cycle routes: They are usually very good quality but they aren't 100% tarmac.
It's often easy enough to find alternatives but it'll make navigation harder and the cycle routes usually take in the scenic bits and they also avoid the steepest mountains.
So for touring they are ideal and you might want to put on some more puncture proof tyres.
The off road sections aren't like NCN/ Sustrans bad though, they are more like hard compacted ground with a bit of gravel.
These are pictures from a signposted cycle route near Lake Constance, which in NCN-style switched between on and off-road sections.
This (on left)............................................................................................suddenly turned into this (on right)
very pretty but not for road-bike tyres.
However I've done a few rides in Germany, Austria and Switzerland and generally found the roads good and the drivers well-behaved. In Berlin I once got stopped by a policeman and told to use the cycle path on the other side of the road (not easy to get to at that point), and observing these rules strictly can make crossing at big junctions
very slow, but I found no more inconveniences than that.
Edit : just realised that the OP was talking only about Switzerland and Austria but these pics are in Germany. My impressions were that all were similar however, and I've ridden with/without helmets in each of them.