They will ask if your yard is fenced, if anyone in the family has allergies, if you're planning to move anytime soon, if you have children, and so on. They may even ask you to fill out a questionnaire for their files, or even to provide references. They don't mean to pry, but they do want to ensure that their precious, carefully raised pups will go to the right homes. If they don't believe you're the right person, they may refuse to sell you a pup. Fast buck breeders are always happy to take your money and hand over puppies without many questions.
Responsible breeders provide proof of registration.
Some might tell you that you could get papers if you're willing to pay more. Responsible breeders put a lot of thought into producing litters. They may ship females long distances to be bred to the stud dog that seems a perfect match. They have females checked for appropriate health clearances, and will be happy to share the results with you. They will also verify that stud dogs undergo similar testing and are clear of known hereditary problems.