Good With Dogs:⬜⬜⬜⬜⬜⬜⬜
Since your puppies are a mixed breed dog, you should sell your puppies for an average of what each puppy will cost you (ie. vet visits and food) divided by each puppy. So an average of $200 - $350 per puppy will let you re-coop your expenses and show you that the people wanting to take a puppy are serious.
The average weight for the Shih Tzu/Yorkshire Terrier cross is between 7-15 lb. The breed is known to do fine with children, but all interactions should be supervised, as the dog as a puppy and adult can easily be injured by children if not careful.
Yes, the mixed breed of dog called Shorkie (AKA: Shih Tzu/Yorkshire Terrier) do shed, however, they do not shed a lot compared to their pure-bred counterparts.
Unless your Shorkie is hot, the panting is most likely a sign of anxiety for your dog. This is something you are going to need to discuss with your vet. He/She will be able to turn you to a Positive Reinforcement trainer to be able to work with your dog on his anxiety when in a vehicle, or he/she will be able to give you medication to give to your dog to help him be calm when in the vehicle. But none-the-less, you should take him to the vet for a once-over to make sure there isn't anything wrong. The movement of the car could be hurting him someway and the panting is his way of telling you something is wrong.