[José M. Villar]

To begin with, I would start by following these tutorials:

https://buddypress.org/forums/topic/bp-103-and-bbpress-which-version-plugins-cookies

http://theeasybutton.com/blog/2009/07/17/integrating-buddypress-wordpress-mu-and-bbpress/

BTW, regarding user mapping, the only setting I changed was WP Admin one, mapped to bbPress Key Master. The other four settings remain untouched.