Question #1

Nick thinks that Gatsby's dream cannot be achieved. The death of Myrtle will anger Tom much more than before, so he wouldn't let Daisy go to Gatsby. Although Daisy killed Myrtle, Gatsby said he want to put all the fault on him. Thus, Tom would think Gatsby as an enemy and never do whatever Gatsby will like. Gatsby has no choice but getting all blame to protect Daisy from Tom. 

Quotation #5

This quote shows that Gatsby is desperate to have Daisy. He thinks all the pasts can be repeated again. Nick tells Gastby to give up since Daisy is married and can’t be divorced. But, Gatsby see nothing but getting Daisy. We could say that he spent at least half of his life getting Daisy. Only to satisfy Daisy and himself, he built a huge mansion near her house. Gatsby held parties in order to see Daisy at his parties. He stayed close to Nick because he was Daisy's second cousin.