Your question is very difficult for humans. It is best answered by machines. Try it.
You proposal looks like you made it up from some documentation. You might find more info from some working examples. I list my dhcpd.conf in an article I wrote on LTSP in a computer lab. My system used a single NIC and had other DHCP servers from that other OS... You need to be careful that two or more servers are not fighting each other. One thing that works is using port 1067 for the LTSP stuff and leaving that other OS to 67. You can get bootloaders that do that from rom-o-matic.net
See the .pdf at the bottom of my webpage for another method checking flag bits.
I used k12ltsp.org . It is designed for teachers, so anybody should be able to install it. ;-)
option-routers give the DHCP server information about routers to pass to the client. Typically, your server will not only supply an IP address tothe client, but DNS, gateway, files to load, etc.
LTSP is great. It allows one to keep old machines running until the fans fall off, and everyone gets to run on a hot new machine. With today's hardware prices, it can be a great bargain. You can put all your money in one state of the art machine. 100 mbits/s is very helpful. It speeds booting and reduces hesitation. If you are very serious, gigabit is becoming reasonable.