Speaking as someone with a dog from a great lineage, I would like to see thyroid added to the list.
From what I understand from my vet, the symptoms to thyroid problems can lie dormant for many years, however, it is possible to capture early warning signs of a propensity towards the illness. I'm not sure how early that can be done, however.
I also believe that thyroid is somewhat heriditary, so at a minimum you'd want to know about testing in parents and grandparents, if possible.
And as someone stated earlier, I would want to know more about their overall breeding program. What are their goals? If it's to breed cute pups, then I would run and run fast. But if they are breeding to attain excellence in standards, titling their pups and weeding out the non-contenders as companion pups, then no problem. Bacca's brothers and sisters are all reaching their Championships (and some might have gotten already, I don't remember). Bacca did not make the cull because he was cyptoid.
I would also look at how many pups they have in their breeding program. There is a limit to what is manageable and still raise social companion pups. And ask how new litters are socialized. I loved that Bacca's litter was raised in the breeder's own bedroom.