Usually the Current Transfer Mode shows “not applicable” when there’s nothing attached to that IDE channel - are you sure your drive is connected to the Primary IDE Channel, and not the Secondary? What other IDE drives do you have hooked up?
What brand of discs are you using, and what burn speed did you pick? For 16x discs (especially when backing up movies), I usually choose 8x.
As for the firmware, I can’t seem to find anything more recent than what you have, but someone else might have better luck.