Firewall/NAT

Hello,

I am going (to try) to replace a Fli4L-environment with m0n0wall (ALIX 2C1) and
I am wondering what NAT-type to select for the following environment.


current setup:
-ZyXEL 652 ADSL router (Mode=Routing/Encapsulation=PPPoP/NAT-Mode=SUA Only
  Start Port=22/End Port=22/IP Adress=192.168.1.2
-Fli4L Firewall (Standard Gatewy for 5 WXP clients) 
 (IP intern=192.168.0.7 / IP extern=192.168.1.2)
-Namp scan of Fli4L-box shows that only port 22 is open (maybe a made a mistake?)


future setup(temporarily):
-m0n0wall (LAN, WAN)
-dyn IP


future setup(definitive):
-m0n0wall (LAN,WAN. DMZ)
-1 fix IP
-local DNS server


I do know I could just try all different NAT-modes, but as a totally firewall unexperienced
person I am happy if as much as possibile miss-configurations can be exluded :-)


Thank's a lot for any feedback!

John