Usually what happens is a new scene replaces an older scene when they both use the same channels. If the new scene is controlling all different channels then the old one stays on.
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 .