In answer to your question yes they do rust around there, I looked a a couple that had rust there.
Tha main issues with them are poorly repaired stone chips on the outside of the headlamps, and those folks whose cars have run without wheel arch protectors, and yes I've seen those as well.....just look on top of the aircon rad, or the oil cooler for the tell tale signs on the ceramic stat.......they do corrode.
Sills go, mainly from the oil lines and mother nature turning the rubber trim as hard as concrete, the bodywork moves, and the seal slices through the paintwork, and galvanising......
But they are few and far between, and you shouldn't let that put you off, any decent repairer should be able to sort it out for a couple of quid.....my windscreen job was £400 all in.....have a look at my website write up on it..
Kevin