BuddyPress.org

1. Rename slugs by defining global constants in /wp-config.php. Eg:

define ( 'BP_GROUPS_SLUG', 'clubs' );

2. Page titles are generated by bp_page_title(), which is defined in bp-core/bp-core-templatetags.php. It looks to me like they are properly localized, though. Maybe there’s a missing translation in the .po/.mo files? What language are you using?