[CentOS] Simple solution for small network in a school ?

Hi,

I have to install a small network in a school in a nearby village. The 
network will be Linux-only, one server and fifteen desktops. Here's the 
idea.

1) Authentication should be managed centrally on the server.

2) User home directories should also be on the server.

3) Users should all have disk quotas, something like 1 GB per user.

4) Some shared directories should be read/write for a defined group of 
users (teachers) and read-only for others.

So far, I've only dealt with local authentication. I have a little 
practice in basic setups of Samba and NFS and managed to get these to 
work OK. On the other hand, I've never worked with NIS, LDAP or the likes.

My question is more general, and I don't want to go into technical 
details. According to the KISS principle, which solution would you 
recommend (or explicitly *not* recommend)? A mix of LDAP and Samba? Or 
NIS and NFS? And what's this thing called Directory Server, which 
vaguely sounds like it's the right way to go?

Any suggestions?

Cheers from the hot South of France,

Niki