Feeding them scrambled eggs gives them protein in addition to what they get in their food.
Feeding their egg shells crushed back to them gives them a calcium boost which helps their shells stay strong. My girls get oyster shell and their shells washed and crushed, for extra calcium.
Feeding them meat scraps will not make the cannibals. They kill and eat mice, bugs, lizards, snakes and etc all on their own and it does not mean they will suddenly start eating each other.
If you provide them proper diet, meat scraps and kitchen scraps is a nice "treat", I stress the word treat because that is not meant to be their only diet.
In the information pages of this site, you can find a list of good treats. Mine love steamed rice, veggies, fruit, oatmeal, yogurt, scrambled eggs, leftover meatloaf, baked chicken, baked fish, pancakes, etc etc.I have yet to ever have a chicken eat another chicken because they turned cannibal after eating meat. I never give them any type of white potato, they do love baked sweet potatoes though.
If one is hurt and there is blood, they will attack the injured one and kill it, if intervention is not forthcoming. That is the nature of the chicken beast, so to speak.