I would be wary of any breeder with 11 week old puppies left unless there was a very good reason for it. Good breeders usually have a waiting list for at least part of a litter and so unless someone backed out last minute or turned out to be unsuitable in the end, it's not usual to have 11 week old puppies left.
If the breeder has kept the pups that long for a specific reason (some toy breeders keep them until 12 weeks as standard for example) I would personally like to see evidence of proper socialisation being done, that the puppy is used ot spending some time away from both Mumand litter mates with only human company and that it has been on several trips out at least and in the car etc.
The breeder should have copies of the KC documents by now and be able to show them to you. Ask to see the parents KC documents too and the breeder should have copies of the stud dog's documents even if they do not own him. They should also be happy for you to contact the stud dog owner and/or visit them if you wish to. Please be aware that all KC registration is (or should be!) Is verification of the dog's pedigree. It is in no way a mark of quality or high standards of either the dog or breeder. Over 90% of KC registrations are from puppy farmers.
The parent dogs must both be at least 2 1/2 years old so that necessary health tests can have been carried out. This will be ^at least eye testing, heart tests and screening for SM and preferably hip scoring too. Some breeders use younger dogs for breeding, but it's not good practice. You must see copies of the results and you can also check on the KC website if you have the parents' registered names.
Why is the breeder breeding? Are they keeping a puppy? If they are not, this would ring alarm bells for me, unless there was a very, very good reason. Do they show their dogs (would have to be a yes for me, again, otherwise, why are they breeding?)
What were the puppies wormed with and how often/when? Was Mum wormed at the same time? Was Mum wormed during pregnancy? (she should have been daily from day 42 until several days post whelping) Yes, if the puppy is vaccinated you should get a vaccination card from the vet.
Have the puppies been checked over by a vet for general health problems, hernias, retained testicles if male and heart murmurs?
Why did the breeder choose the stud dog they did? (Look for answers such as good pedigree match, repeat of outstanding previous litter, excellent health test results, not something like 'it was my mates dog'... or 'he lives nearby')
The puppies should obviously be kept in clean conditions, be on four meals a day of good quality food (not something like Bakers, Pedigree etc) have free access to Mum, be either kept in the house or have daily access to the house, have some garden/outside access. At 11 weeks I would expect them to be mostly toilet trained and understand basic commands too.
I haven't remembere deverything, I will probably add to this later...