Compx National Mailbox Lock 4C Style Clockwise

It's described as a clockwise lock. Does that mean you turn the key clockwise to unlock it, or clockwise to lock it?

Where can I buy the cams (latches) only for this lock?

What is the outside dimension. The round part where you insert the key?

Can the mailman open this lock with a post office master key to put your mail inside your postbox and then lock it up again