Okay... bread isn't good for chooks or any birds. It gets stuck in their crops, which can cause constipation and them to go egg bound... bad bad bad.... ouchies...

The best thing is for them to free range and get bugs out of the gardens and fruit & veg scraps. I used to buy my chooks a bunch of spinach a week as well. They love green leafy veges. Layer pellets are good and remember that a chook can't lay eggs without extra calcium, so either you can get shell grit at the place you get hay etc... get a medium course ground one, or you can grind up sea shells yourself if you are near a beach.

I wouldn't give chickens meat, but they do eat snails and lizards etc... so they do get meat that way... sometimes they break their own eggs and eat them. But personally I wouldn't do it. My grandma used to throw all scraps including meat/ham/chicken scraps to the chickens and they ate them

Cat food is high in fat and protein, so maybe not designed for chickens? They need a low protein and fat diet.