Hi Mark,
I was working through some of the same problems that you had this morning, and I think I found some solutions.
1. Register Page
This page seems to automatically redirect to the homepage when you are already logged in. Since you pretty much have to be logged in to work on your site, I’m guessing that’s what is happening to you. If you logout you should be able to see it. I went to your site and it worked for me.
Additionally, the login itself is handled directly by WordPress, in a thin little bar that floats at the top of the website. (Again, you have to logout to see what this will look like for your visitors.) I find it ugly and counterintuitive, so I added the bbPress login widget to the side of my site. Seems to have the same functionality, but I’m still in very early stages of testing.
2. Forums
If you have enabled group forums and/or sitewide forums, the default CBox/BuddyPress settings conflict and render the forums unusable. From what I can tell, group forums are handled internally by BuddyPress, and sitewide forums are handled by bbPress. This creates a conflict over the “forums” slug.
What you need do is delete the “forums” page, then be sure to empty it from trash. Create a new page called “Group Forums” (or whatever you like) and then associate it with “forums” under Settings -> BuddyPress -> Pages. Then, under Settings -> Forums, make sure you have “Allow BuddyPress Groups to have their own forums” checked. In the box below that, I have them set to the forum root even though bbPress doesn’t suggest that. But so far things seem okay for me.
Hope that helps. You can poke around what I’m working on here: http://commons.fieldnoise.com/