Shelf liner works great if you use a plastic tub for a brooder. When it it time to change the liner, pop in a new one and run the old one through the laundry..after rinsing out the poo though! The shower is good for that or a hose outside
Unless it is a sexlinked cross or an auto sexing breed, the only way is vent sexing. That is done by an expert and just after hatching. If done correctly it is more than 95% accurate