I already answered this on discord, but i figured i'll do this here too in case someone stumbles upon this post in the future :)
1. The internal build of the game has the ability to bind the jump and slide/roll button to the left/right mouse button. This feature will be available in the final build of the game.
2. I'm not aware of this issue. (Probably a bug that was fixed a while ago? The public alpha is quite old compared to the internal build)
3. No plans for a Linux version. (Mostly due to technical hurdles.)