You can do that, have a roo only pen if they get along.
If you want to breed, it depends on your goals. They're already mixed so purity is not a concern as is. If you just want cute little chicks, then any bantam hen will do, pure or mixed.
Japanese mixes. The clincher was rooster number two- he looks just like what a Japanese mixed with gold Sebright would look like. Including the rose comb. p.s. I like this roo a lot! Just beautiful to me.
It looks like the first roo might have some leg feathering. Last one has a beard...