Body, lenses and batteries are the priority for cabin baggage - note the difference between guarunteed cabin baggage dimensions and the "if we have room for it" dimensions in the airline t's&c's. If you're above the guarunteed dimensions but within the normal dimensions they do have the right to take your bag at the aircraft steps and put it into the hold if the plane is full. They seem to be far less likely to do this if you're a Speedy Boarder - so paying a bit extra may be worthwhile if your practice packing run has you cutting it fine on the dimensions.
I'm not sure about the Quantum batteries, my guess is that they need to be in protected cases/sleeves and should go in your cabin baggage. Wherever they go, they must be secured to protect the contacts and prevent a short.
Lightstands should go in your hold baggage (as would a tripod). Lights and flash guns wherever you can after you've sorted the cabin bag priority gear - but the batteries go cabin baggage and make sure they're cased/protected and not loose. 7DayShop do some very handy AA and AAA battery cases. ThinkTank do some very good ones for camera batteries (and they'll also take AA/AAA).
Security don't usually bother with camera gear, but with this amount of gear assume you'll get pulled for a hand search and swab through your cabin baggage and leave enough time for getting through security. Oddly enough, even with the heightened electrical checks this summer was the first trip in a while I wasn't pulled for a hand search through my camera bag.
