Oh, all this sounds horribly familiar. Spent the best part of 4 weeks trying to get a wireless router to work. In the end it was a simple case of IP addresses. We'd had every component (MAC, WEP and all those other nasty ambiguous things) right at some stage, but never had all of them right at the same time ... too many variables you see.
But... once we phoned the right person (i.e. Mr.SmartArse who actually knows this stuff), we set it up in 5 minutes, and connected a third computer to the network in less than 2 minutes.
The moral? Don't call me. I still don't understand it. But do call someone who does understand this stuff, and they'll talk you through it on the phone in no time at all.
You just gotta phone enough people until you find the right know-it-all.
As for firewire - call a Mac nut. They understand firewire inside out.
But don't call me
