I don't know if it makes a big difference- the case would be handled by one of his assistants, and they would not be able to drop the charges without his permission or supervision I would think. Perhaps he is preparing to drop the charges, but doesn't want to be the guy actually dropping the charges in the eyes of the Durham public. One can only hope that this will soon be over.
No. He's removing it from his office. If he was going to pass it to an assistant in his office, he wouldn't have to file to do that. Recusal, in this case, means his entire office is recused. It's not a re-assignment.