I know when our dog was that young, we told our pup "don't bite" or "no teeth" and we would hold her snout as we said it (nothing firm, rough or abusive). The "no teeth" was used, especially when we were playing with her or giving her food and by saying that, she learned to move her lips (are they called "lips"???) over her teeth so the teeth wouldn't hit our hand. I never wanted a child to think that my dog snapped at them, if they ever fed her a snack. Eventually your dog will pick up on the repetitiveness of the command and will learn not to do it. I don't see how that is a terrible reprimand, especially if you have young children - you wouldn't want them in charge of "spraying" anything at a dog but you do need to give them some authority to train the dog. I've never used a spray, as your one post described. I think the worst thing people do is to not work together, as a family, and train a dog. Everyone should be responsible for training the dog in a consistent manner. We also provided A LOT of chew toys, bones, etc... and every now and then would find one of those 'baby" teeth, when they fell out.
As far as the time period, for us, it seemed to last for at least 8-9 months or longer ( I don't quite remember). The baby teeth bites and snips were painful - it was nice when she was out of that phase.
As far as bathing, I did give our puppy a bath more frequently - sometimes once a week, usually every two weeks. However, it is so important to brush them, daily, and this could help keep her coat clean. Also, in this season, she could be rolling in things outside that is causing her fur to smell doggy. I don't have a yorkie. My pup's about 55 lbs. I currently have switched to an oatmeal bath-type shampoo that seems to be milder and soothing on my dog's skin. It is also helping with any environmental allergies that she may be having, as I am not seeing her chew/scratch on her front paws as much.
What a great dog (I hope YOU still think so!). I have a friend with a tea-cup yorkie and she is awesome! Very fun and playful - quite the little character!