Okay, first, could you please make a backup of your KS02 firmware and e-mail it to us?
The difference between KS04 and the patched KS04 is whatever the filename says it is... in this case, only "cf" is present. "cf"--crossflash--firmwares simply have the EEPROM checksum verification subroutine disabled, which will allow 1673S drives use a 1693S firmware. Since your drive is a 1693S and not a 1673S@1693S, this would not affect you in any way.
KY01 is the firmware for the Sony DRU-800A, which is a LiteOn drive with an expensive Sony sticker affixed to it. The difference between KY01 and KS04, aside from KY01 carrying a Sony name, is how old they are. KY01 dates from March 8. KS04 is from March 29.