Oogie Boogie's goal is to be the scariest person in Halloween town, obviously he despises Jack, but he's scared of him. He just wants to bee him. :)
The dress is called the red court dress,google in shopping and only one will come up in the search
Her name is Colleen Atwood, and she actually won an Academy Award for her designs on that film.
Jack Skellington is a resident of "Halloween Town" in "The Nightmare Before Christmas" (1993).