Thanks a lot for playing the game and for taking the time to write down this detailed feedback. I'm glad you enjoyed the game, I'll respond to your three main points as you raise some good issues that need to be addressed:
1) My bad for not mapping multiple keys for the menu. I'm still deciding between the old Unity input system and the new one, so I didn't polish that aspect of the game in this demo. Will upload a new version in these days.
2) Weapons durability is shown in the UI in the top right, the blocks behind the weapons represent the durability, but the feedback for losing them is basically invisible and I'm still trying to find a way to explain it to the player. I'd rather do it organically than with a prompt, but I have to deal with this as soon as I can.
3) Hints are a great idea. I had the idea of placing them around the room (as you suggested, a scroll or something written on the walls) but probably will probably make the Reset Sphere the holder of these hints, so by pressing one button you will Reset the room, while with another you will ask for a hint. Maybe 2-3 hints for each room.
Again, thanks for playing the game and for your precious feedback!