VLAN configuration

I want to implement a VLAN on my 250 user LAN.
We have Nortel 450 switches and an Accelar GB switch that connects the stacks from each wiring closet.
I need some tips on DHCP assignment to the different VLANs once they are in place. Do they need to be different subnetted networks? Can I use one network segment address and still configure multiple VLANs?
I’m thinking of setting up each wiring closet as their own VLAN.
Email and File servers and printers would need to be linked with all VLANs. Additional VLANs would be setup for server/client specific groups.
I understand the benefits and need some help with the details.

Thanks for you help!
Pat