Re: Homepage other than Activity or Admin Blog (or a WP page)
Some days I’m a little slow. We already have an example of this in bp-default with the ability to select either the activity stream or blog posts as the front page. Unfortunately I’m not quite understanding the flow through the various hooks and filters right now. I think what you need to ultimately do is something like the following:
locate_template( array( 'groups/index.php' ), false );
In bp-default, this is done (well, with activity/index.php) in a function that filters page_template.
This should be really simple and if you can crack the egg, it opens up the ability to set any page as the front page.