If you need to request permissions from an author or publisher, here are general guidelines, plus a sample letter you can customize.
Fair use allows you to use someone’s copyrighted work without permission. However, invoking fair use is not a straightforward matter. Learn the 7 questions to ask to help determine if your use might be considered fair under the law.
Asking an editor or agent to sign a non-disclosure agreement is not part of traditional publishing business practice.