The breeder applies to the kc and puts forward their affix they have made up. If there is no objection then the kc approves it. The breeder then has that affix and pays a fee to maintain it.
As only the breeder can register their litters, they have to send the names for the puppies. Alot of the time a breeder will use a theme for their litter. They put forward two names for each pup, a first and second choice, and most of the time one or the other is approved.
Some breeders let you choose the name for your pup. I was lucky with my second pup from the same breeder that I named him.