I agree with BabyGirl Rosie. This breed is a very high maintenance dog. The brushing alone can be daunting to someone who isn't use to having a dog with long hair. Even if you keep them short, the cost of grooming is really expensive. I keep mine short and that alone gets expensive. I don't know if you've worked out with your parents the cost of care, who's going to pay for what, and who would be watching him/her when you go off to college (if you want to go to college). Are you going to take the pup with you? Some other things you need to consider is Yorkie health. A few illnesses that are prevalent in yorkies is bad teeth (require daily teeth brushing, dental cleaning and teeth extractions when needed), collapsed trachea, luxating patellas and liver shunt. There are others, but these seem to come up the most amongst the forum.
As far as barking goes, I have thankfully been blessed with a quiet boy. He doesn't like to bark for the most part. He whines and cries, and even screams like a monkey. He does bark if someone is at the door, but with a little bit of training it doesn't escalate past a few warning barks. The whole barking thing is new for him.
As far as your other dog, has he or she ever been around another dog? One thing you can do is have a dog play date with a friends or familys dog. Have both meet on neutral territory. If they're ok with each other, then you can try having both dogs in your home. I do transport for a Yorkie rescue. Whenever a new dog is coming into my house temporarily, I always bring my baby, Kaji, so he can meet them. Then I take both home and Kaji isn't surprised when he sees them in his house. If I'm lucky and their personalities match up, they play and have a great time. So far, we've had great experiences. Only once did Kaji not like one of the fosters. The foster dog was disabled and needed all of my attention, which Kaji did not like at all.
We're not trying to discourage you from getting a Yorkie. They're absolutely wonderful! They're just a ton of work and can get expensive.