I don’t know about your second question, but with almost every proton-ge update I’ve gone into Steam and switched over to the new version with no issues so far.
Maybe that’s a no-no for some games but, again, no issues so far.
EDIT: Same goes for wine-ge whenever I have games I bought through GOG and play through Lutris.
2060 - The True and Definitive Year of the Linux Desktop (maybe, probably not but hopefully)