When you go to make a new listing, in the "Create an Ebay Listing" section at the top of the page, there's a drop-down menu that says "eBay Site". There you can select what you want.
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 .