Do a search for the contacts you want to export. Under Edit select all. Under file choose export address book entries. Name your file choose a lacation to save it to, and choose a file type. That's it.
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 .