I'll be honest, I know nothing about hamsters but I saw your thing about cage size and thought that it didn't seem quite right as with other rodents the advice is to get as big as possible. This site suggests the same:
dwarfhamsterblog.com/#prepare
Find out if you have any family friendly hamster breeders around you. I have rats and my local NFRS breeder also breeds hamsters, mice and gerbils. I've been in her shop and have been able to pick all four types straight out of the cage with no issues. The hamsters I had as a child would nip if you went near them.
Breeders are usually better than pet shops, who buy animals from rodent farms more often than not. Do not believe the signs in pets corner and other shops about buying from proper breeders, I've been in various ones who admit that they gets theirs from a rodent farm in Essex, I live on the south coast of Sussex so the poor creatures are being driven down in large groups in small boxes. Also ask to handle one of them, if a shop doesn't let you, don't buy from them.
I don't know if certain breeds are nippier than others but being handled from a young age certainly does affect things.