The weather can be unpredictable pretty much anytime in the Alps but it does'nt usually keep raining for days on end...if you get a wet day it ususally is dry for the next few.Snow is not unusual on some of the higher passes even in August.Local knowlage gleaned from cafes and bars can help here.
Grossglockner is well known but they charge you for the privelage of riding it and anyway in my own opinion is not the most spectacular or most beautiful of passes.The Stelvio beats it for my money as there are 3 aproaches to choose from,and there are others that are unsurfaced that are higher and have better scenery but obviously are not R1 material!
Regarding the local fuzz...i've been stopped every time i've ridden through the alps,only ever in Switzerland, and only ever to have the E marking checked on my silencer! Which gets fun when they are told the E marking is facing the right hand ally case and is not visible without taking said case off...i've never had to take it off yet.
Just going for a short ride on my bike....