Always have treats ready when you want to brush him. Start doing little at a time and be sure he is calm. Even if you have to brush once and give a treat right away. Once he knows he will get a treat after brushing, it will be a different experience for your baby. I also suggest silk harness as it doesnt get their hair matted as a regular harness. YT member
chattiesmom sells those here.
As for the grooming I know a lot of people love puppy cut on their yorkies. You have to be careful though when you mention a puppy cut to the groomers. Each groomer think of a puppy cut a different cut. You have to be very specific to the groomer what exacly you want to be cut and how short.
Hope it helps.