Also, if oyster shell isn't available or within your budget, you can finely crush (almost powder) eggshells and feed to them. I have a tray that sits in my microwave when not in use, that I put all my cracked eggshells into for the girls. I don't wash out the bit of egg white that remains, just...
I'm no official, but I don't see anything glaring that will be really harmful. If your weather is anything like the mid-Atlantic states in the US, there should be green grass and bugs on the way! Chickens love this type of food, and will do very well on not much more. If you have access to...