Reputable breeders (the ones that I know) will let their kittens go between the ages of 3 and 4 months, some of them if they are able a vet to do it will have the kittens spayed/neuteered before they leave their home.
Siamese cats need human contact, so they do terribly if left in cages. The mothers with their kittens are put in a small room by themselves when the kittens are quite young, they they are integrated with thier other cats.
It is not rare to find the male sharing the responsibility of the kittens, even if the kittens are not his.
Whe you visit the breeder's home look at the condition of the cats, shiny coats and their weight, well the mother may be a bit thin, but that's expected. If you are looking at wedge type cats, they don't have any underfur, so if the mother is a little to intent on cleaning her kittens some of them my have some bare patch on their body (Ha!, Ha!), not to be confused with ringworm.
When you take your kitten home, you will also get his/hers vet record (shots, etc), and his/her cat association (CFA, CCA, TICA, etc) papers. If he/she is not neutered/spayed you may be able to get them only when you show proof that it has been done.
Good breeders want to better the breeds they are working with, not make money, if fact all of them loose money breeding cats. They go to shows, and can be picky about the people they are selling their kittens to.