How much bedding in brooder

You'll only need paper towels for a few days, until your chicks have figured out what 'food' is. They will eventually start picking the paper towels apart if left in there. Mine will start doing it at a week old.

When the chicks are on the bedding without paper towels, a couple of inches deep should be fine. They will scratch around in the bedding, helping it to stay dry. I add shavings at least every other day to my brooder because they kick so much of it out. My brooder is a wire cage, surrounded by cardboard (to keep drafts down, and to help keep the shavings in). I've never used a completely enclosed brooder, so I have no experience with keeping one of that sort clean and dry. I like mine because there is better airflow and it has never gotten stinky. I currently have 21 standard chicks in the brooder. Four bantams ought to be super easy to keep clean with a minimum of effort.