I want to start off by thanking everyone again! I'm so glad I stopped lurking on this forum- I've never had so much helpful insight all at once!
He's definitely still a tool (for instance, he broke his stall guard in the couple of hours he was in for the night) but now he's an attentive tool!
Since starting some of these tactics he's starting to be more respectful of my demands. Last night I tried asking him to stand still while I undid both rows of the gait and put a rope halter on him, and with the magic of the ever present dressage whip, he did! Then this morning, even though he was running free from busting out of his stall, he walked in the barn of his own accord but did stand for me while I threw his halter on and led him to the stall (as opposed to just throwing grain in his tub and letting him run in... which was tempting).
He's also lightening up on the teeth (at least in my direction, can't say the same for his turnout buddies), and has yet to strike out at me since our new rules started.
Again, thank you everyone for making me see his nasty behavior didn't warrant an excuse! I think I might leave her a nice list of decent trainers to look at when she gets home though...