Fenway Park uses Hebrew National Kosher hot dogs to the best of my knowledge. In my opinion they are one of the better tasting hot dogs made. The buns are standard hot dog buns again working from memory, and dressing is always mustard then whatever else you like, ketchup, onion, pickle relish, etc.
The dogs are steamed, I think the buns are heated above the steamer.
Chicago and New York dogs get a bit more strange. NY dogs are most popular dressed with light mustard and cooked onions. Chicago dogs may have sliced tomato, slaw or anything else within arms reach.
Always dress the dog and not the bun. Put down wet ingredients like mustard, ketchup or Mayo (yuck not on my dog) then chunky ingredients like onions, relish, slaw, cheese or kraut. Mustard may be put on top of chili. Cheese and onions should always top chili. Never add ketchup to chili dogs and real hot dog lovers say after you reach 18 you should never put ketchup on a hot dog.
Did you know July is National Hot Dog Month?
Jane Mansfield was Miss Hot Dog in 1950.
Babe Ruth once downed 24 hot dogs between games of a double header.