From what I've read, and heard from my sons travel program, is that it is initially open to all. You go to the showcase, get a rating and then then they will be selecting Regional teams for the big Tournament
Do a search, the gentleman, who is hhelping get this started, posted quite a bit about it a few days ago. Looks pretty legit, with the people involved.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .