I found out these tricks for hunter survival while doing some instances:
During Steamvaults, Feign Death is very useful. If you feign while under the effect of a blizzard (casted by Naga Sirens I think), you won't take any dmg. Also, the first boss uses a very dmging storm. It hits for 2300-2500 every 2 seconds, so if you are in the middle, it will do about 5500 dmg by the time you get out of it. You'd become immune to this effect if you feign. I don't know why this works, but I've tested it and it works...it may have been fixed, but I hope it hasn't.