There was a problem last night with auctions that posted after 7:30 PST. There is a whole thread on it over at listings. Lots of people were having manual posts and schedule posts not being posted to eBay. Listing Thread Link
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 .