(Answered) Piloting Skill Rolls & prevented or reduced damage

[Yeti]

Does damage that gets reduced because of equipment like CASE or Ferro-Lammellor armor still count for determining if there is a PSR for 20+ damage.

1. armor that reduces damage like reflective, reactive, hardend, FL, do i count the damage before or after the reduction?
For example a mech mounting Ferro-Llammellor armor gets hit by a single ac/20, which reduces the damage to 16 points, does he need to roll a PSR for 20+ damage or not?

2. damage prevented by CASE
A mech that already has lost all armor and all but 1 point IS in the location mounting a Gauss rifle and CASE gets hit by small laser that crits the Gauss rifle. So it takes 3 points of the small laser and 20 points of the explosion, but 19 of the 20 points just vanish, does he need to roll?

3. attacks hitting mechanized BA or swarming infantry on the target mech.
An Omnimech that carries a points of elementals gets hit by a single ac/20, that hits the side torso, so 11 points of the damage kill the single unlucky trooper and only 9 points actually damage the mech. Roll or no roll?

[Xotl]

Does damage that gets reduced because of equipment like CASE or Ferro-Lammellor armor still count for determining if there is a PSR for 20+ damage.

1. armor that reduces damage like reflective, reactive, hardend, FL, do i count the damage before or after the reduction?
For example a mech mounting Ferro-Llammellor armor gets hit by a single ac/20, which reduces the damage to 16 points, does he need to roll a PSR for 20+ damage or not?

You count actually-inflicted Damage Points.  So your Ferro Lamellor armour example, the 'Mech would not need a PSR unless it is inflicted with at least 4 more damage during that Phase.

2. damage prevented by CASE
A mech that already has lost all armor and all but 1 point IS in the location mounting a Gauss rifle and CASE gets hit by small laser that crits the Gauss rifle. So it takes 3 points of the small laser and 20 points of the explosion, but 19 of the 20 points just vanish, does he need to roll?

It does not need a roll, it suffered a total of *3* damage in your example.  The small laser destroys the last internal point before transferring its remaining 2 damage to the next location.  The Gauss Rifle, which explodes prior to the transfer of these 2 damage points, no longer has any Internal Structure to destroy.  It inflicts net 0 damage to its 'Mech, although the MechWarrior still takes 2 Pilot damage from the explosion.

3. attacks hitting mechanized BA or swarming infantry on the target mech.
An Omnimech that carries a points of elementals gets hit by a single ac/20, that hits the side torso, so 11 points of the damage kill the single unlucky trooper and only 9 points actually damage the mech. Roll or no roll?

No roll: the 'Mech suffered 9 damage.