Ron jotted a note for Viktor to send along with his message to Bill, so that Bill would know it was actually Harry and him and Hermione who said to contact him. He voiced a token protest about going to Viktor's, but since they had little option he gave in quickly.
He can have gotten dinged in the fight with something minor.
I have no DE to offer up. I'm still not sure how that happened. This is why the character limit should raise. /kidding.