Nick,
Be careful plugging in a firewire m-audio device ( or any external FW and USB) if your computer is not turned off. It is best once to start up once the drivers have been loaded and the computer is being started after being completely shut down, once connected it's best to just leave it connected. Of course if you travel it is fine to disconnect but reconnect it while in the shut down state then start up. I have the M-audio Ozonic firewire keyboard and it has a on/off switch, it powers through the firewire cable and in my case it is a fw 400 cable. There are fw 400 to fw 800 cables and adapters available, on Ebay they are a few dollars be careful not to order it from Hong Kong, there are plenty available in the US, I suggest Ebay because every-time I try to get these cool 400 to 800 adapters they are sold out, but I actually love the 400 to 800 cables too. Obviously 400 is half the speed as 800 but there is a little brother to these connection called firewire iEEE 1394, it is like a micro sized connection similar to mini-usb. The speed of the iEEE 1394 varies per system and cable.
As far as connecting dual monitors. You can get the proper adapter from the Apple store or Apple store online. Look up the manual for your system on Apple.com in the support section and it will actually tell you exactly which adapter to use.
I am currently using two systems, With my PowerBook G4 I can connect a monitor to it, and when the system is started up (seeing it is always best to connect cables with no power source connected to any item, monitor or computer and once it is connected the power source may be connected again as well and the system started up, in order to prevent frying or surging) It should recognize your monitor, I have a "24 Acer and I had to only pick which monitor would be where as to it's position to on screen movement. It recognized the proportions and everything perfectly. So I at that point have the option of running dual(split) screens or I can just run the laptop with the lid closed and using only one screen, if I choose that, but I have tons more success with using dual monitors. I just got a Mac Pro and I am super excited because now I will be connecting two FULL sized monitors.... All for music and video work...
I hope that doesn't sound confusing, if you open up your monitor selections at the top menu bar between your Bluetooth setting and Audio volume adjustment setting, you can then choose the correct monitor settings if they have not already auto detected like mine did.. It is nice too.. but the Acer has DVI. I also have a Vizio monitor which I tested my G5 connected with a DVI adapter from the computer to VGA on the Vizio monitor and my Mac found it as soon as the start up was complete and perfectly, it matched the screen resolution and looks beautiful as well.
I love Apples because they are actually fun to work with, I don't mind trouble shooting if you have problems so hit me back if you have other questions or if I have completely scrambled your brains with all the jargin of Firewire and Dual this and that.. Who knows you may have figured this all out before now but either way.. blessings in your direction.
Keep on Keepin' on....
Kelcey