Well I feed mine Royal Cannin Yorkie junior. It is specially made for Yorkshire Terriers. I am in UK so we are a bit limited. When I first got her the breeder had her on Pedigree dry mixed with wet. She was having issues with diarrhea and vet said to only feed dry kibble and she along with several others said that the Royal Cannin was one of the best. I will admit it smells wonderful... kind of like chocolate meat ... sorry I love chocolate. I know I would never ever give it or let Tali have access to chocolate ... but I can't say the same for myself.
I have been giving her just tap water and here it has a large amount of limescale in the water. So much so that if you don't descale regularly you will need to replace any appliance that uses the water mains: washing machine, dishwasher, kettle, and coffee machine. I haven't seen distilled water for sale here but then again they may call it something different that I am unaware of (sometimes confusing being American here

same language but so different

). Been here 10 years and still learn a new word for things every once and a while

.
I will see about the water but worse case scenerio would be give her Evian if I can't find distilled. Thanks about the Q-tip trick I will definately use that. Tali's tear stain isn't crusty just wet but since she is young don't want it to stain her face. My mom had a poodle that had tear stained face and I always thought she would look so much better without it but my mom said that was just how they were and you just had to live with it. I am not good with that assessment ... I am just as stubborn as a Yorkie