Legal Question in Business Law in California

You get signed consents and releases to use the contents of the interviews.

Mr. McCormick is completely on point. You will need to contact the people you interviewed and potentially the people depicted in the story. The reason for this is that people among other rights have the right to publicity, which prevents others from using their name and likeness to for a commercial purpose without their consent. For this reason, without their consent you could be sued when you start publishing your book.

........and you copyright the book. You might consider taping the interviews (with permission) so you'll be able to check your memory of what was said, and later have proof that you didn't misquote. Finally, you might re-ask your question under LawGuru's "Intellectual Property" category so that it goes to experts in that field.