I'm not sure why that's the only breed you'll consider. I'd be OK with any dual purpose breed and would look for a straight run bin hoping to get several cockerels. But that is your decision.
Pullets are different from cockerels in that they don't get the hormone rush during puberty the boys do. The meat does not get as flavorful or develop the texture nearly as quickly as the boys do so you have more flexibility as to how you cook them. You are probably looking more at when they quit growing rapidly instead of worrying about texture and flavor.
I don't butcher my pullets very young. I butcher my cockerels at 16 to 23 weeks as that suits how I raise them and cook them. I typically butcher my pullets at 8 months after I've seen them lay eggs so I can pick which ones I want to keep as replacements. So I haven't paid that much attention to their rate of growth. To avoid feeding them a lot with practically no weight gain I'd think around 16 weeks at the most.
No idea but it will not be much. Pullets just don't put on the meat like cockerels do. Even when I let them go to 8 months there is not a lot of meat there. Pullets are not efficient to raise for meat. You can eat them, I do eat mine, but I raise them for other purposes and eat them instead of selling them.
