I breed ragdolls on a hobby basis.
In terms of personality - despite what people will tell you, they really are just a cat and their personalities vary enormously. I currently have a mum and daughter, neither are aggressive and have never scratched or bitten us. They are both pretty clever and savvy. They rule our Doberman and steal her bed. On the ragdoll Facebook pages I am on I see tales of the stereotypical dopey ragdolls and the stories of utter nutters that will tear people to pieces! I personally think from my experiences of litters I have had, you get an assortment of personalities in each one, though I haven't yet had any aggressive ones in my litters so I think mum and dads sweet genes come through.
Tips for buying - check you are happy with the way they are being brought up. I think if they are in a secluded pen - not good, best to be raised as part of the household with other pets, lots of noise, I've found mine being raised around my kids has made them fairly bombproof. Check what food they are on, if it's something like felix or whiskas I would have concerns as the breeder is considering the cost rather than the best start for the kittens. Check the vets documents to be sure they have definitely had their checks. Take the free four week insurance that should come with them if they are registered.
Any cat nip toys keep them happy. The feathers on sticks are always a winner.
In terms of colours, happy to advise, what questions have you got? Definitely not a problem for mum and dad to be different colouring, it means there will be a range of colours to choose from in the litter. What colours are mum and dad?
I think a litter tray up high is possible long term, less so when they are a kitten as it needs to be easily accessible for them. I only have cheap litter trays for kittens because I have to have quite a few and because when you have lots of kittens I just empty and refill completely once a day any way plus poop scoop as and when needed so I don't need any fancy trays. When I don't have kittens I just have a standard hooded litter tray which works for us but you kind of have to find out what your cat likes best. Also make sure you use the same litter as your breeder to ensure the kitten isn't put off when they first come home. You can change gradually over time if you want to.
Feel free to ask any questions. xx