Razor Wind keeps tripping me up because it's a Normal-type move when by name alone it sounds like it should be a Flying-type move.
Also, is there something special about Twister that makes it a Dragon-type move as opposed to a Flying one?
While I agree, I found this on Bulbapedia regarding why Twister is a Dragon-type attack:
The Japanese name of Twister, たつまき (竜巻) Tatsumaki, literally means "dragon spiral", and refers to the belief that dragons spiral around themselves to form the shapes of twisters.