Who co-created 'Seinfeld' with Jerry Seinfeld?

In which city is 'Seinfeld' set? What is the name of the diner where the 'Seinfeld' characters often eat? What is Kramer's first name in 'Seinfeld'? Which 'Seinfeld' character is Jerry's nemesis and a mail carrier? Who played Elaine Benes in 'Seinfeld'? In which city is 'Cheers' set? In 'Cheers', what is the name of the bar owner played by Ted Danson? In which city is 'Frasier' set?