I agree... looks like the valve itself is leaking but that whole thing is easily replaced. You'll be a toilet fixin' guru in just a few minutes and feel like superman. Make sure the wife thinks it was really difficult and required lots of skill so you can get treated like the king of the house that you are.
See above. Also make sure you don't screw it up and wife has to use a bucket until you get a plumber out...or you'll be the king of the garage.