Ports on a firewall

Which webserver is CF tied to? Typically, when running in standard or mult-server mode, you won't use any non-standard port. You would have CF configured to run on top of Apache or IIS, which would serve the templates up over the web standard port 80 for http traffic. The port number applied to a specific instance is the port connection between the webserver and CF/JRun instance. Aside from webserver config you also have to take into consideration DNS. For instance, I have several sites configured within Apache, many pointing to different CF instances (with their own ports per instance), but they all run through port 80 to the browser. I have to configure my system's host file to view the sites (dev only stuff) from the server, as they aren't listed on any DNS server.

You shouldn't have any issue running dual NICs on your server. In fact we have three on one server. Your routing will be defined by the IP settings you apply to each NIC, how your switch may be setup, how DNS is directing traffic, and the configuration of your webserver. Disabling your LAN NIC shouldn't have killed your web content, unless your webserver is improperly setup to use it's IP block.