Just following on from The Odd One. Insurance is a brilliant idea. Chances of one laptop in a teenagers hands, being dropped/nicked/screwed or otherwise compromised is three times higher for you!
A way of getting over the smaller hard disks on laptops and especially given that you plan on a wireless network, is an external network hard drive. They are up to 450GB in size and the users keep their own portion of the disk. That, is very cheap insurance in itself.
With all the data whizzing around your network, don't go for anything less than a 108MB/Sec transfer time. If you go for 54MB sec it will slow down quite a lot if everyone is using at the same time.
Conan