OK, router patched into this strange server system, but the eventual configuration is odd, thus:
Not that you can tell, but the 10.* address connected out of brimstone to the router is actually the old external connection. Things got weird when I connected up to the router with the secondary network card ... but at least its working. Mostly.
I'm having trouble accessing the webserver by name from within the firewall, but not from outside. Its all rather odd. But headway is being made.
On the other hand, ftp seems to be down from outside, but not inside. Stranger and stranger.