1. How do the individual forces compare when the rider experiences a normal

sensation of weight? What is the acceleration value when this occurs?

The rider experiences weight or does not experience weight depends upon the direction of the elevator in which it moves and its acceleration.  

Explanation:

Consider the mass of a rider as m. So its actual weight is mg and it acts vertically downward. The apparent weight of the rider is depended on the acceleration of the elevator and its direction of movement.

When elevator moves with a constant speed i.e. its acceleration is zero, the apparent weight of the rider is equal to the actual weight. Thus the rider's sensation is normal.

If the elevator is moving upward with an acceleration a, then the apparent weight of the rider will be more and the rider will experience an increase in weight or the sensation is heavy.

Or when the elevator moves downward with an acceleration a, the apparent weight of the rider is less. And the rider sensation is lighter.