Actually, the Iron Golem and TRex have the same encounter rate, it's just that few people fight on Tiamat's floor 2000 years ago for extended periods of time. Even if you go for the Masamune, you probably won't encounter more than ten fights or so. Warmech may have the same, although I kinda edited my original ROM's encounter rates, so none of my files has the correct number. What was really funny was when I went into Ice Cave and fought Warmech with a level 13 party. :P

As for the Zombie Dragon question, I assume it has something to do with thieves, and some type of magic. Or maybe just thieves. Or it also may be a trick question. I'm kind of leaning towards the third one, myself, because not even the game designers have patience enough to get a thief high enough to run from one of those things. I don't.