So many of those supposedly confusing aspects asked by people vis a vis BP templates have been covered by us in fair depth on the BP codex though:
http://codex.buddypress.org/themes/theme-compatibility-1-7/a-quick-look-at-1-7-theme-compatibility/
http://codex.buddypress.org/themes/theme-compatibility-1-7/template-hierarchy/

Seems a shame to need a plugin to to manage this aspect of BP templating and obviously if activating the plugin on another theme styles are not necessarily going to be compatible.