I don't set foot in fast-food restaurants, either in the U.S. or anywhere else, so I can't say.

As for fountain drinks, you'll find Coke (and, quite often, Diet Coke) in cans just about everywhere in China. I happen to like watermelon juice, which is usually whipped with ice. Never had any problems at all. Similarly, never any problems with fresh scallions when eating Peking Duck, though I usually have that only in Beijing. I don't eat unpeeled fruits or vegetables unless they're cooked. One of my favorite winter street foods in Beijing is roasted yams. There's no opportunity to wash them (which kind of destroy the point of eating them, i.e. getting all that hot, yammy goodness) and, again, I've never had any problems.