Disable NAT on WAN and routing WAN interface to All other LANs interface

dcarb1

Hi to All,
i need to use pfsense like in internal firewall, connected to an external firewall via WAN interface.
So we have some problem to route the traffic from the external firewall and DMZ to internal LAN ( here a litte schema )

|EXT FW(192.168.8.254)| –--> |PFSENSE(192.168.8.1)|
| |
| |
|DMZ(172.16.0.1)| |LAN(192.168.10.0/24)|

192.168.8.254 has the default GW to 192.168.8.1 for the network 192.168.10.x
192.168.8.1 has the default GW to 192.168.8.254

With NAT disabled, all the traffic seems to stop on the WAN interface (192.168.8.1).

Some question :

Has the WAN interface the ip-forwardin enable like other nics ( lan / opt ) ?
Does the WAN interface work like a LAN interface ?
It is possible to use pfsense like a router and use a WAN interface ?
It is possible to use pfsense without a WAN interface ?

I have done a lot of test, but nothing has worked.
Someone can help me ?
Thank in advance.