Hint: Often you will need to talk to someone who isn't around at the moment, or rummage about in the effects of someone who is. Usually a quick jaunt out of the room and back in again will achieve the desired change in occupancy.
Hint: When fleeing the bomb blast, hug the right-hand side of the screen and run like stink. This will maximize your chances of surviving...and you'll still be able to get in a few choice words from the unfortunate bioengineer.