Answer to: Can I switch upper cases?The cases are physically identical. It will have a sporty 2-tone look, for sure.
Answer to: No FireWireIf you have firewire devices connected and they are recognized by your Mac, System Profiler should be able to list the devices. If it does not, I would try logging out and logging back into a different account, and trying System Profiler again. If you get the same result (no devices shown), try zapping PRAM (hold down Command, Option, P and R keys simultaneously when booting the Mac, and keep holding them until you hear 3 or more startup chimes).