Multiple WAPs and roaming

I'm about to set up a bunch of WAPs in a school to enable the kiddies
to wander about with the school laptops, drop them, break their toes -
you know the kind of thing.

I'm intending to have these all on one SSID, each with their own AP
name.

I have two detail questions.

First, do the WAPs need to be on the same or on different channels?
If different, do I need to space them apart in any way (eg use every
other channel).

Second, do the encryption keys for each WAP need to be the same?

tia

jay