Can't really give you advice on how to tell people about your area, since I don't really know it. But I guess the big thing is maybe knowing a bit of the history about your area, or other interesting tidbits. Figure a way to try and help people become excited about your area/country or interested in learning more, even if they don't know the first thing about it coming in. (Or think that nobody in England has heard of a dentist).
Dealing with "awkward" customers is pretty easy. If you've waited tables or worked with the public before, you can have the idea. In general, an awkward customer might be one who tries to hit on you, or maybe seems too enthusiastic, etc. How would you handle it or steer their interests back to what it should be, or try and defuse the situation?
As for living with people of different nationalities, answer that however you want. Dunno how your son would factor into everything, but I could say that in general, You are working at EPCOT. Think of it as a cool mini World Showcase at home!