Misc: What US state is nicknamed, is the 'Blue Hen' state?

Questions

Back To The Future: Back to the Future 3 was set in one of Doc's favourite places, the __ __?

Back To The Future: In BTTF 1, Marty & Doc must wait for _ so that Marty can get back to 1985?

Back To The Future: In BTTF 2, Biff is rich in 1985 because of a book given to him in 1955 by ..?

Back To The Future: Marty & Doc travel to 1955 again to prevent young Biff from receiving the?

Back To The Future: Marty gives a _ to the Doc in 1955 to prevent Doc from being killed in 1985?