For those who are looking at this thread, I'm still plugging away at this experiment of mine.
I figured out all the ports to leave open, and put rules for them on the WAN interface. Everything not covered by rules on that interface gets a deny, correct?
Do I have to put these rules on the Lan interfaces as well? Because right now, the only rules on that interface, are leaving ports 80 (http), 443 (https), and port 1433 (sql port). As well as a forwarding rule that says anything coming in gets sent via rdp protocol to a specific machine. But each lan interface has the default allow all rule (you guys helped me understand that rule, thanks again for that!).
Edit: if I changed those rules on the wan interface, to floating rules. Would those rules apply to everything the firewall does, instead of individual interfaces?