This is a difficult question to answer, and one that seems more difficult for a Ragdoll breeder, as most people are lead to believe that the Ragdoll cat, is more of a mythical creature that have extra traits, or they are more than a "cat". Ragdolls kittens, just like most kittens are very interested in playing, and if the breeder is properly socializing the kittens, and it sounds like they are, since all the cats and kittens were in the room, and didn't seem shy or scared. Our kittens depending on ages, young kittens sleep a lot, the older they get, it seems they go full blast, and then are more likely to snuggle next to the person, or in a lap.
I can say that our Ragdoll adults, most of them, will come up to our visitors, allow petting, and some actually demand it. Then we have a couple of Ragdolls that are more likely to just come sniff you, and walk on to find a nice place to nap. It would be my strong opinion to say that the Ragdoll traits come out more as the cat matures. There are many factual traits regarding the Ragdoll, however, in breeding, not all traits may be there. Such as the Ragdoll is a very relaxed laid back cat, this is fact. Some will say, the Ragdoll will just fall limp when picked up, this is not true. Each Raggie will have it's own personality. I have some that love to be carried around like a little baby, and while sleeping can usually be found, with the belly in the air, doing the "flop". I believe it is a general fact that the Ragdoll is a social breed, but nurture will always play a factor in any particular kitten/cat. The Ragdoll does require minimal grooming typically, it does shed though, it may be less than other breeds, but shedding is still going to be an issue to anyone who is bothered by shedding. The breed is not hypoallergenic, if one is allergic to cats, the Ragdoll breed is no different. Ragdolls are a large breed cat, and while you may see some sites quote 25-30 lb cats, this is very rare, and for the most part an over exaggeration to promote ones cats. In actual a female is usually 10-15lbs, with males being larger. Neutered and Spayed cats will be a little larger, since the breeding hormones are not affecting them. My Ragdoll alters get between 15-20 lbs at full grown, which is typically around 4 years of age. That isn't to say that there hasn't been larger Ragdolls, but it just isn't the average to see those sizes.
Now, I also will say our cats act completely different when we have visitors than when we are just relaxing as a family. I could swear to you that most of my Ragdolls will fetch, but they would make me look like a liar if you came over and I tried to put one of them on the spot..
Most of our Raggies sleep in a bed with one of us, but we do have those that prefer the top perch of the cat tree. I will say many of our adults are lap cats, but one of my favorites, well he is just too big to be comfortable in anyones lap, but he is very much an, in your face, headbutting, cuddle bug.
If you are not set on pattern or coloring, you may ask the breeder to pick the kitten out for you, she/he sees the kittens all day, so would know the kitten who would be more likely to be the lap kitten.
Also, once you get a kitten home, you can do certain things to encourage behavior, including helping them to enjoy lap time. Depending on the kittens individual personality, you may find that in time the kitten enjoys lot of lap time, or will only tolerate it for a short time, and is more comfortable getting attention in other ways. However, my best advice with Ragdolls, is asking the breeder to help you choose the right kitten for you and your family.
It sounds like the breeder had a nice clean home, that is great!! The adults and kittens, I assume were healthy looking, since they were out roaming. If you go back to this breeder when the kittens are old enough to be seen, try interacting with them with a toy, or picking each one up, and see which one is the least "wiggleworm". Just remember in the back of your head, that they are still full of energy kittens.
Another thing is, ask about the personality of the Mom, I have found that for the most part if the Momma cat is more extroverted, her kittens are more likely to follow suit. So ask about the personality of each of the breeding adults. You might ask for referrals as well, and ask past adopters what their Ragdolls temperament is like now that is an adult.
I may have gave too much information, but there are many myths that surround the Ragdoll breed, and educating those wanting to adopt a Ragdoll should know the full facts. There is even a myth, that Ragdolls feel no pain, the breed originator, Ann Baker, came up with this theory to further the breed.