A. That he was born as James Gatz which he changed when he was seventeen, to Jay Gatsby. He was grew up in West Egg. He dropped out of college after two weeks. He got a job as a fish monger on Lake Superior where he met a man named Dan Cody  who gave him a job as his assistant on his yacht. Which made Gatsby love traveling. Also because Cody was an alcoholic which made Gatsby not want to drink. When he died he left money to Gatsby but because of Cody's mistress Gatsby did not receive it. Gatsby was determined to become a wealthy man on his own accord.
B. The actual details about Gatsby and his background differ completely from the rumors that have been said. The rumors made him out to be a mysterious and devious man who possibly killed a man. When in actuality he was a poor man who grew up normal and worked really hard to get where he is. He was and is a hardworking man who made his status.
C. That he changed his name to Jay Gatsby because he didn't want to remember his past life or the man he use to be. He changed it because he wanted to become a new person. He wanted to be a prosperous, wealthy, respected man. He wanted to choose a name to represent that.  Gatz was a poor man who didn't have much to be proud of  and wasn't that popular. While Gatsby is a wealthy man who has a lot to be proud of  and is widely known.
D.  Tom doesn't like Gatsby at all. He acts like he has something against him. Tom thinks that the fact that Gatsby earned his wealth is something to be looked down upon.  Also Tom is jealous of him and Daisy, because he wants Daisy to himself and thinks that Gatsby isn't worthy for both her and him. Tom also wants Daisy to stop seeing him and seems to not trust Gatsby.