Firewall/NAT

I am in the process of setting up a monowall firewall for our office network.  What we have are multiple public IP addresses, one that I have assigned to the WAN, and the other two are actually assigned by their respective computers.

The two computers with public IP addresses are attached to OPT1, which I have bridged with the WAN.  I have forwarded the ports for email and webservices, and I can access the email server via the web.  The email was working before I made the switch to monowall so my MX records and everything is set up correctly and I havn't changed anything on the email server.

I have turned on Advanced outbound NAT, although I'm not really sure what that is supposed to do.  I made a single rule to go along with that as a "LAN to WAN hide rule"

Running 1.32 of monowall.  Is what I am doing possible with my current setup?

Little bit more information.

One computer is VPN/FTP.  I can access the internet from that computer and I can verify that it is using the IP address it assigned to itself but I can't access the ftp from the internet.  I can however ping it.

Other computer is the email server, I can access the web portal for that computer from the internet, but it is unable to bring up a single web page.  I can not ping this computer. 

Should my gateway be the ip address for the WAN or should I use the gateway my ISP recommends, or does that not matter?  All my IP addresses are static.