Most of these are agnostic to being on Linux, and 1 is intended since it's before a final choice can be made involving the gym quest.
2, the majority are well documented.
3, known thing
4, is a bug with how the save system displays timestamps, can happen at multiple times in a day/hour
5, known font issue with Linux, look into getting the ms-fonts put in your user folder. Or use Proton via Steam to play the game.
6, endings are planned to be potentially reworked.