What are the details behind the way Wordpress stores user authentication data?

authentication wordpress passwords credentials

Wordpress uses the Portable PHP password hashing framework. See also this question: What type of hash does WordPress use?
By default this association is in the wp_usermeta table under the wp_user_level key
Not without a plug-in (or without editing editing Wordpress' code or database)

You might want to look at the code for bbPress because it will share Wordpress' user database.

CodeHunter