What to look for if adopting a puppy from a stranger?

There is a seven-month-old shiba we are visiting because the owners supposedly can no longer keep him. They say they were in a house and are now in an apartment where dogs are not allowed. I'm on a waiting list with a few breeders, but would love to help this dog.

What questions should I be asking? Also, is it fair to ask to bring the puppy to a vet (with the current) owner before purchase?