Re: change default blog
This is actually more tricky that it sounds, because BuddyPress by default stores most of its information in the blog ID = 1, and it will ignore most other constant settings. If you are installing BuddyPress for the first time, and change any of the BP_ROOT_BLOG or BLOGID_CURRENT_SITE or SITE_ID_CURRENT_SITE variables, BuddyPress still saves most of its information in blod ID = 1.
https://trac.buddypress.org/ticket/823 references this issue, and I’ve included a patch for the instances where this occurs.
lynnallan, I’m afraid there isn’t a core solution for what you want to do yet, but the patch in the trac ticket *should* better prepare BuddyPress for this type of installation.
My only other suggestion, would be to think of it as WHERE the data is in the database doesn’t REALLY matter, unless you’re trying to split server load up across multiple database servers. That being said, you can install your corporate theme on your root blog, and then install the bphome theme on another blog, and then use the WordPress page template ability to recreate the look and feel of a BuddyPress on a blog other than the root. This is kind-of how http://leadpress.com/ has their site setup, if you need an example.