BootCamp should be able to get the “wasted” partition back without trouble. BootCamp is a BETA, meaning that it will most likely expire if you keep using an old release. Most likely they will ask for a few bucks to continue using it (how tough? BootCamp is basically a partition manager, with some drivers, and added stuff to the firmware on the Mac. My guess is that nothing will happen, or that, lol, drivers for windows will expire. That would be hilarious.) or just getting Leopard that ships it in full form. A thing that i heard, is that the final release of BootCamp will have that WGA (Windows Genuine Advantage or something similar) to prevent the use on a pirated copy of Windows. This might worry somebody, if it’s true. I don’t believe it, anyway.
Finally, you can’t absolutely boot Windows from an external drive. Sure, the Mac supports it, but Windos dosen’t. Firewire? Izzat sum MAC mumbojumbo? is most likely what you’ll see on your screen if you try Windows on FireWire, :D , and since Windows initializes and resets the usb halfway during startup, giving you a funny gray screen, with an apple in the middle. Yes, you just had a wonderous auto reboot. (personally tested, it won’t work. There are hacks that fiddle around with the startup sequence, but it will only lead to a more unstable Windows, and it’s pretty a difficult operation)
The good news: Intel Macs support booting from both USB and FireWire, so you could place a backup copy of OS X in your video iPod, and boot even tough it supports only usb for data transmission.
And finally, the resizing of partitions has been around for ages… at least in the Windows world.
Summary: BootCamp supports only Windows XP ServicePack2 install discs, and due to Windows limitations you can only install it on an internal drive.