Can you block someone on fa?
Its possible that someone can be blocked from this site. You'd have to ask the founders. So, don't quote me on this since I'm only saying that's its possible.
Yes, as "saucybaby" said. It just makes it so the user cant contact you, they can still view all of your stuff though (ie. questions, profile, comments).
Yes you can...Just go to their profile and on the left hand side of the page you will see a link saying 'Block User'.