lol. Not sure about the firewire specs. Could be the 800, could be the 400. I would suggest
http://www.iriveramerica.com and have a little look at the tech specs.
To clear up the recording issue, yeah most MP3 players can record. You plug in your diskman, or other external device and they record straight in, but the reason is works is because they're not true signal only line-outs (i.e. there is power in the other device). Microphones do not supply there own power (unless they have a built in preamp, which is a special bit of kit and most wont (if your mic takes batteries, it has a prearm)). Therefore there is no power coming from the mic, and you can't record onto the device. The IRiver is the only MP3 player I know of that preamps the microphone port, meaning I can use my pro microphone with it to go outside and make professional quality recordings.
All other MP3 players would require me to buy a preamp unit, which is an annoyance, cos you have to keep changing the batteries - plus it's not very convenient to hold. But I appreciate to the vast majority of people, this makes no difference and they won't need it.