Am I getting ripped off? A plumber quoted $325 to winterize my 110 sq. ft, 1930 house.?

You for ripped off on the winterizing, but since you hav e already paid him it is a done deal with verbal fulfilled contracts, thus you have no recourse. As for your present problems, they can be attributed to age. Learn from all this and get everything in writing when you get a NEW PLUMBER