in-house, home office route tables

ISP modems, gateway boxes, most third party network devices default to a Class C IP address something like 192.168.000.000/16.

See Private IP Network

I want to separate my work traffic from my home traffic
using a Class B IP address something like 172.16.000.000/12.
Clearly my access points and router boxes will use Class-B configuration
for all of my work things.

Can someone help me sort out Route Table Entries or other
LAN configuration details so that this works reasonably well?

Some issues that I have no idea how to address:

• there won't be any DMZ servers in Phase-I deployment
• my primary access point/router will need to interact with the Class-C primary router.
• my Class-B devices need to access some Class-C printers or resources
• some Class-C resources need to access some Class-B printers or resources
• mobile & hand-held devices need to work everywhere but do so securely

Will I need, or is it a preferred deployment, to have a configured DNS in either the Class-C or the Class-B LAN?

Thanks in advance,
~~~ 0;-Dan