Why Ski Challenge 16? Because it is last game of the serie "Ski Challenge", and still the most popular up to this day, as you can see on the forum : https://www.forum.happytec.at/

Why do you need the patch OC:20? Since the game is no longer supported by its developper Greentube, and therefore lacks of servers, this patch is needed to be able to play the game. Making the latest patch mandatory just helps simplifying the verification process.

Why is it forbidden to change your ski settings between tracks in Any%? To keep the "Any% feeling" of the run, otherwise it would be much more "coherent" to allow ski changes and multi-segmented runs. However multi-segmented runs of this game would make no sense, because it's a personal best time based game, and therefore would just be a back to back collection of each of your best tracks.