On Stitch, the key is to have them sit up as TALLLL as they can; that way the harnesses are very loose. I do it myself, because I don't like that squished-spine feeling.
On ITTBAB, have kids sit on the edge of the seat or on your lap, preferably with their legs folded indian-style. That will avoid the sting and the scurrying bugs effects. Also, having them NOT wear the 3-D glasses is a good idea the first time around.
One of the best things I've found for distracting nervous kids is to have them search for hidden Mickeys on the ride. I suggested it to a couple near us on HM a while back, their school-aged daughter was terrified. I told her how to look for the Donalds, and her Dad told me it worked, that she was so busy looking for them that she pretty much forgot to be scared.
You *can* get out of EEA in a true emergency. During the dark parts of the ride you are being observed by several CM's. If you call out that you have an emergency and signal for help, they will turn on the lights and get you out, but it is a very complicated process that will cause the ride to have to be shut down and recycled, which, if you've ridden it, you will realize is a time-consuming thing.
I was once on the Jimmy Neutron ride at US when a man in my row (seated next to DS) had a panic attack because of being confined by the lap bar. About 45 seconds before the end of the ride he started trying to climb out of the car. An employee saw him and hit the emergency stop, which froze the ride instantly and brought up the lights. The problem was, it also locked down the lap bars, because the cars were about 6 ft. in the air at the time. We had to wait until they they went through the entire safety check procedure procedure and re-set the ride mechanism; which meant that the man ended up trapped in the ride car for another 35 minutes, along with everyone else who was on the ride with him. He was sweating and shaking, and contorting himself in all sorts of directions to try to get out from under that lap bar. THAT experience freaked out DS (then 6) a bit -- he had never seen an adult fall apart so completely, let alone 6 inches from him.