The triple entente peace treaty
The cotton gin was a machine for separating cotton from its seeds.
He was 18 years old because he was born in 1989 and the film came out at 2007,
so 2007-1989 = 18
Explorers were fascinated by the artifacts in the New World because they believed that there is a mythical city of gold named El Dorado. They thought that they have found it there. It tickled their imagination and enjoyed that fantasy.