Since we can answer only one question at a time about a particular work of literature, I will address the themes of this story. I have included a link below that will help you with the remaining part.
The primary theme of this story by Fitzgerald is the quest for wealth and what people are willing to do to keep their wealth. John comes from a town where wealth is worshipped, and this has shaped his view that one cannot be both "free and poor". Fitzgerald aptly names John's home town Hades, a name for hell, alluding that "the love of money is the root of all evil". Braddock Washington has allowed his love of his wealth to make prisoners out of his family; any visitors his children bring home must be killed, so none of them can never have true friends or prolonged contact with the outside world. But even worse, Washington has lied to his black slaves in order to keep them enslaved. He has no qualms about kidnapping and killing anyone who threatens his lifestyle. There's no doubt about Fitzgerald's theme when everything is destroyed at the end of the story.