I have a question concerning remakes of American films but also remakes of foreign films.

Is someone familiar with the process of buying the rights for a remake? Do we apply the exact same rules than for a derivative work?

Has someone seen a contract for buying such rights? I am not actually planning on buying the rights of any movie, but I am just trying to figure out how that works, and discover how american studios can buy the rights of so many foreign films (except money).

Thank you.