A breeder-specific community would be awesome, I think.

As for eggs... well, Ryner's only had one brood so far, and I've been kind of planning to try to keep his output kind of low anyway ... But as for a cap... If there's going to be one, a per Pokémon per x amount of time one would probably work best. I think it'd probably be a little unfair to have a per Breeder per x amount of time thing, since some Breeders are just able to handle more Pokémon than others (just based on personality). But per Pokémon per x amount of time would work.