There is a way to tell if they are boys or girls at a young age. They do this at commercial hatcheries, take one in your hand carefully, and outstretch one of its wings. Look at the feathers towards the tip. If it seems as if there are two rows, one long and one short, then it is a pullet. If they are both equal length, then it's a cockeral. I use this method and am almost always correct. This is because females grow their long feathers faster than males.
As for bedding, I use straw. After one hatch in shavings, where there were some small shavings mixed in with large, I was looking at the chicks, and noticed they had shavings up under their eyelid. I had to use blunt tweezers to remove them, and set them on straw after that. I really is healthier for the chicks, because they don't try to eat straw as much as shavings, and shavings can hurt them when they are young.
As for bedding, I use straw. After one hatch in shavings, where there were some small shavings mixed in with large, I was looking at the chicks, and noticed they had shavings up under their eyelid. I had to use blunt tweezers to remove them, and set them on straw after that. I really is healthier for the chicks, because they don't try to eat straw as much as shavings, and shavings can hurt them when they are young.