Baking stones provide a steady baking surface that absorbs heat, and then radiates it evenly, helping the oven to quickly recover heat loss.
The baking steels can be placed above and on the rack that you'll be baking your bread. This ensures consistent heat all the way around your loaf.
Moisture in the oven needs to be added after the door is opened to add the loaf. Otherwise, you'll lose it when you open the door. A water pan can be added prior to baking, or along with the loaves.
My preference is to add a water pan during the preheating stage rather than while the oven is hot.