In modern bucket seats the risk of whiplash injury is incredibly minimal. Your head doesn't have the distance to travel far enough to hurt your neck. On the other hand, standing on the brake will cause both vehicles more damage and cause the other car to decelerate more quickly, causing the occupants to experience more acceleration in a direction in which the restraints are less effective (getting pressed into seat-belts and airbags hurt more than getting pressed into a seat).
Standing on the brake is simply shifting the energy around at the expense of the other party
Yep, which is why I think it depends on what's in front of you. A human probably doesn't have enough time to analyze the situation and determine whether or not they could do better than holding down the brake. A computer can probably do better in some situations.
Well that depends in where you want the momentum to go and how rapidly do you want to and can afford to dissipate it, does it not?
I mean, if the impact is strong enough, you'll be sent flying whether you are or aren't holding the brakes. Just that if you're not, your steering wheel is still going to steer.
The kind of things I wish driving school could teach you. I don't know how, a set of busted cars on a driving loop with mild collision so you'd know what it feels and how to react. Kind like wet roads and collision avoidance classes.