Most chickens will eat pretty much anything you feed them. I'd try just giving them the peels the way they are now first and see if they eat it that way. But you can grind them up if you want to. Either way would be fine.
Yes, I'd see if they'll eat them as is. Mine eat just about anything. They love their greens, esp in winter when there isn't much green to be found, it'll be real good for them. :bun I just love these cute cows!