[K12OSN] Internet in k12 AND windows/macos?

[gKw-X]

Hello,

The school currently has a lab of computers booting to k12, an LAC room 
full of Macs, and various Windows machines scattered here and there. It 
would really turn some heads if I was able to have every machine in the 
school able to boot to either k12 or the local os, AND to have internet 
access in either case. The current setup has the firewall/internet 
server hooked into a switch, which goes to all the mac/windows machines 
and into the k12 server. Then the k12 server goes into a second switch, 
which connects to all the lab pcs. So there are two things I need to ask:

1) Do I need two DHCP servers? How can I do this without running into 
conflicts on either the k12 machines, or the local os machines? I tried 
just plugging everything into one switch and suddenly half the k12 
machines stopped booting (I assume because they were talking to the 
wrong DHCP server).

2) Can Macs boot to k12? There are some notes here and there indicating 
that maybe they can. How does this work? Or am I completely clueless.

Thanks!
Matt