Welcome to the joy of keeping chickens. I have had my ex-batts since March so am relatively new to this too. I can tell you the following though! Firstly it is possible for a chicken to turn into a cockerel although a sex-change is very very rare!!! Layers mash is good. I use layers pellets. About 2 to 3 handfuls per bird is about right plus a handful of corn per bird.. I always let my chickens have access to grit. You could give them some oystershell too to help harden the egg shells. A couple of my girls lay shell-less eggs. Could be lack of calcium. As far as treats from the kitchen go mine adore grapes, melon, spinach, kale,broccoli, tomatoes, apple, pear, plums, nectarines, strawberries, blueberries.......in fact most things! I don't give them potato, onion or leeks. They are not keen on carrot peelings. If I give them bread I only give a small amount and soak it first. They do lay less in the winter. I am currently getting 4 to 5 eggs from 9 hens. Hope this helps.