How old are they again?
Can you put down old clean towels they are easy to use for a couple of weeks till they know the difference between shavings and food. TSC has thicker shavings and most feed stores carry horse bedding that is what I use. Towels can work because you can take them out shake...
Just keep them off of slippery surfaces. it can cause leg problems
They sure are messy. You'll probably have to change brooder sizes many times before they go outside.