person coming from behind
In almost all cases if one vehicle hits a vehicle from behind the rear vehicle is at fault. There are some extreme instances in which that is not the case, but it is a case by case basis.
In most states it is no one's fault when ice blows off a vehicle and hits the vehicle behind. There are different circumstances that may come about if the ice causes an accident, like a car skidding off a road, though. It depends on the laws of the state, who is at fault when that occurs.
Answering "Pulling out of a parking lot onto a street and you have to back up to avoid on coming car and the car behind you hits you who is at fault?"
The person who hit a parked vehicle is at fault.
A stopped car shouldn't hit anything because it's not moving. If a car hits the car behind it must have been in reverse and front ended the vehicle. In that case the car that front ended the vehicle is at fault.
The rear car would be at fault for not making a safe pass.
This depends on the situation, but if you were stationary, not moving and he hit you, he would be at fault. In most cases if the other motorist hits you from behind it is his fault, as you must maintain full control of your vehicle at all times, and if he hit you from behind, that was not the case.
Assuming you're talking about a parking lot situation, generally there is no way to establish fault in such an incident. Unless you're a fan of the old "Brady Bunch" TV series. A 50/50 fault, where each driver pays their OWN repair costs.
it could be both. depends on the situation. if you didnt see the car coming its there fault. the car shouldve slowed down or moved over to aviod hitting the door.
Assuming the other vehicle was in the right lane - you.
the truck behind the other car
The car who hit you is at fault , however if you did not have your brakes applied , and if having them applied would have prevented you from hitting the car ahead of you , you would be partly to blame for hitting the car ahead of you. That issue depends on the speed that the other car hit you and the distance you were from the car ahead of you