Well I think there is a breedng FAQ around here somewhere... That should have some answers. Also I think most cornsnake care books have good section on breeding, and caring for eggs and hatchlings as well.
So I assume these are what you have for the hatchlings:
http://www.cosycritters.com/shop/images/575035.jpg
The snakes will probably be fine in those for a while but be careful, I remember hearing of a snake getting out through the clear plastic top. I dont remember the circumstnaces though.
I would say for heating you should line the back of a shelf or two with 3 or 4 inch flex watt and simply place the hatchling cages a little less than half over the flew watt.
When the eggs hatch around day 60 you can remove them from the egg box as soon as the get all the way out of the egg. As far as I know there is no reason to leave them in any longer. Of course they will be perfectly content in the egg box as well for a few days so you have an easy window to move them into their new homes.
One other thing to think about is what you will do with the snakes later on. Do you have homes/buyers waiting? Something like that.
Good luck with them!