It depends on the school. Of course, with thin (or fat) clients, there
is no installation necessary, apart from the ltsp servers. Schools who
use full workstations can install them via pxe boot from the main
server. Ltsp servers can also be installed that way. The standalone
profile is for machines that will move out of the skolelinux network,
and is like a normal debian installation.
There are no user accounts on the machines, not even the full
workstations. All accounts exist in LDAP on the main server. (except
the standalone profile). No-one can log in anywhere if something
happens to the main server (which it doesn't in my 10 year experience,
fingers crossed)
There is backup of the main server. Other maintenance isn't catered
for. Personally I use parallel-ssh to keep workstations updated. I
also have clonezilla images of key machines.
Perhaps someone else will fill in some more technical details for you,
or maybe you have more questions now?
cheers
Nigel