Dreyadin is correct. Just like anything that dies, rigor mortis sets in. You must let the bird rest for a day before consumption if you want it to be tender. As far as I know, it doesn't matter if it is rested in the refrigerator verses the freezer. Although you could brine the bird, it isn't...
As everyone else said, you won't get much by trying to breed out your CRXs. However, if you are interested in breeding your own meat chicks, you have a few options. You could raise a dual purpose breed (like barred rocks), or you could try to cross-breed for your own pseudo-cornish cross chicks...
