They aren't that delicate; water quality wise, they can tolerate moderate amounts of nitrates.
Those tankmates you listed sound like fine tankmates. Fish in the box/cowfish family need peaceful tankmates, and those fish you listed aren't known chasers, nippers, etc., so I think you'll be good there.
I have personally never experienced the tank poisoning, and have read that in the species you have, this is particularly rare. This most often happens from the longhorn cowfish. If you run sufficient amounts of carbon, this may go unnoticed completely.
If a poisoning would happen, you would need to run carbon to remove it from the water, and maybe do a few water changes. I do not believe that this toxin has any ill effects on humans, although I wouldn't advise sticking your head in the tank for a drink of water, obviously.
Lastly, I'd read through this website for further information, it's very good:
www.cowfishes.com
I hope I was of some help to you!