I'm not an expert by any means Dizzie!!!! but thank you for the thought!
I use either clean old pillowcases, or when we have a lot of chicks, clean old double sheets on the floor over the shavings. Don't use sawdust as the chicks could eat too much of it. But how old are your chicks? For the first 3-4 days they run around on the pillowcase and poop all over it, but the only thing they can eat is the chick crumb. At the end of the 3-4 days I carefully peel away the pillowcase or sheet to leave nice clean shavings underneath. I don't wash the sheets, just keep looking out at auctions and boot sales for them really cheap, but its different if you are only rearing a few at a time.
They can't slide around on the sheets either, so helping to prevent spraddle leg.
With temps, if you don't use a thermometer, the chicks will tell you if they are warm enough, if they huddle under the heat lamp they are too cold, so lower the lamp a little until they are a bit spread out under the perimeter of the heat with a small gap in the middle. That means they are just right. If they are out at the far corners of the brooder, they are too warm so raise the lamp a little. Temp wise we start them off at 35C at day old, reducing it by 2 degrees each week until they are 4 weeks (5 in the winter). Ours will go outside at 5-6 weeks depending on the season. But when I was in scotland a couple of years ago, Aggy had her 2 week old chicks outside in March for a while each day and they were fine, but we did sit and watch them for ages to make sure they were okay!
Like Dizzie said, I don't give our chicks treats either until they are off heat, then I start them off with a little bit of chickweed, then go on to a few dandelions, but they don't get stuff like corn until they are 15 weeks. They don't need them. they get all their nutrients from their feed