回答“Can I switch upper cases?”The cases are physically identical. It will have a sporty 2-tone look, for sure.
回答“No FireWire”If 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).