First welcome to Yorkie Talk. Another fellow Canadian!
Only a very experienced breeder can guesstimate what type of silk coat and coloring a puppy "should" mature into. what Maximo has posted in terms of the quantity of hair on the legs is a good but not perfect indication of the type of coat, not necessarily the color of said coat.
There are a whole lot of questions you need to ask when interviewing breeders. I'm not sure why you lost your 2, but if it was from health issues, or even not from health issues, you want to try your best to get a puppy that will be free from genetic problems.
My advice is to research the breeder first, get them to email you their health guarantee, customer contacts, their breeding pair's registration information. Find out what the breeder does in support of their chosen breed. Do they show, do they train in obedience/rally/agility/field/dance/dock diving, do they support the rescue efforts, are they a member of the National Club
www.cyta.ca.
In terms of actually looking at a puppy any puppy, do your homework on the breeder first. All puppies are adorable!. You want to observe the pup in action when you visit. With their littermates, chasing after a toy, then finally with you. When you pet or pick up that puppy. Pick up to inform yourself. Look at their eyes, are they clear, are the whites bright, eyelids look normal, normal blink response? What is the shape of the head, size and set of the ears. Smell the ears, the mouth. Only a milky smell should eminate from the face. Ears should have NO smell. Look at the teeth, nice and white? No obvious gaps, gums pink?
Either you or the breeder pick up pup under chin, and between legs. Wait until pup relaxes into the suspended hold. You want to see all four limbs hanging straight down, with a level top line. Look from the side, look from the front. Now observe again puppy gait. Does pup travel in a straight line? Does he vary the pace of his movements? Is it always a quick rush, then a flop down?
What kind of curiosity does he exhibit? Startle response is? Has the pup been Temperament Tested? REsults of same.
ask to see the parents . both hopefully. Ask about the quality of silk of the parents?
If which will be rare the parents are in full coat; feel that coat. You can't miss a true silk coat. What does it feel like? Well take a silk pure silk scarf from you or your wifes drawer and run it over the back of your hand. It feels cool, and soft, and flows like water over your hand, right? Well that is what a pure silk Yorkie coat feels like!
Finally if you tell me where you live in Canada I can try to direct you to some shows in your area, where you can meet the breeders and see what they are showing. The Purina National is on this upcoming wkend, and would be a great event to attend if you are in Ontario.