You should be able to boot off of this CD. My guess is that the CD did not burn correctly - try making another and check the ISO file to make sure the md5sum/sha1sum matches.
Make sure you can boot off your OS X CD if you still have one. This will ensure you can actually boot from CD (and didn't disable it somehow in openfirmware).
I burned my Ubuntu disk from an Ubuntu i386 system. A Windows machine should be ok.
Non-Apple keyboard should not matter. I do know that the boot is touchy and you may have to mash C (press & release it at different times) - holding it down on startup may not work.
If you only have a PC keyboard, the open-firmware shortcut is Alt+Super+O+F instead of Command+Option+O+F. Super is also known as the "Windows" key.