"Two skiers, different weights (50 kg, 100 kg), same track, who is faster, what formula?"
Neglecting air resistance, and assuming weight is the only difference, i.e. identical techniques, etc. both will arrive at the same time. This idea has been demonstrated at the tower of Pisa by dropping two balls of different weights, and they (almost) arrived at the same time on the ground.
For a free fall (vertically downwards) with no air resistance, the time t to descend a height of H from rest is given by
Since mass is not included in the formula, so the two balls reach ground at the same time.
For skiers, there are differences, such as:
1. size of body, which affects air-resistance.
2. skiing techniques, which includes many factors.
Sorry that I am not able to respond im Deutsch!