Hi,
As you are planning to have web dispatcher installed in front of all the application you need to first find a network which is different from the network where all the application are installed. The zone in which web dispatcher is installed should act as DMC zone.
Specific ports should be opened on the firewall between web dispatcher and other application to bypass trafic.
All the traffic should be secure using ssl protocol and web dispatcher can do SSL offloading and url filtering.
I don't understand why do you need sap router for that.
Thanks
Rishi Abrol