
All breed clubs will have A code of Ethics, which will vary in soem details from one breed to another regarding age for breeding, number of litters in a lifetime. They will vary far less on the side of responsibilities of the breeer. An example for my breed is here:
http://groups.msn.com/NECGB-NorwegianElkhoundClubofGreatBritain/ethics.msnw so you can use such a code to ask your breeder questions and they shoudl adher to thes principles agree within their breed as best practice.
If you read the links you will see why a breeder should be breeding so asking along those lines as to why they are breeding, but maybe not quite that bluntly. A real enthusiast will tell you what they were aiming to accomplish by breeding a particular litter.
Depending on the breed you will need to ask what health screening has been done and the results.
With living creatures nothing is guaranteed, but the whole purpose of pedigree breeding is as far as is possible to get what you are aiming for. the importance of the pedigree (the ancestors) is their traits. A breeder looks at the parents traits when deciding to mate a bitch to a certain dog, but as you know you don't just inherit your characteristics from your parents, you may have granddads nose, great grandmas varicose veins. Your Great Uncle Pete may have had Heart trouble and some of his children too, maybe you are carrying that trait in your genes and if you marry someone with that problem in the family your children may be a t risk.
These are all things both physical , health and temperament wise that a breeder is looking at when breeding pup hoping for that perfect pup who has it';s ancestors outstanding point and none of their weaker ones. Of course some pups may just be nice and typical rather than outstanding as maybe their ears are a little larger than ideal or they are a bit longer in back or nose, but these are really minimal differences that you probably wouldn't notice unless your judging them against each other with an ideal in mind.
What you don't want and have probably seen plenty of are Yorkies the size of a Cairn or Westie, a Cavalier King Charles the size of a Springer spaniel. A breed with great floppy ears when they should be upstanding.
Even worse you don't want dogs with timid or vicious temperament that are the result of a breeder who doesn't care if the parents had good natures their only reason for being bred from is that they could reproduce, and as this breeder will have forgotten about the pup and you as soon as your out the door and your money is in their pocket, what do they care if your dog grows up to be a nervous wreck going to the vet with one ailment after another.
With an unverifiabel pedigree or non pedigree yu are simply takeing piot luck, but you can guaranteee nothign ahs been doen to maxmise your chances of getting what you hoped.