WELCOME TO YT
I am no expert, and I had many breeders to chose from when I got Cali.
I do strongly believe that you buy the breeder first and then the pup!
I do see the red flags you indicated and dishonesty in any area on the part of the breeder would put me off immediately. Unfortunately, one hears of so many people who fell in love with their puppy and then ended up spending $$$$$$$
because they were not well bred.
Hopefully, one of our knowledgeable breeders will weigh in to give you there perspective on your search.
Good luck. - the perfect Yorkie is out there for you, just be patient!