I don't have a staircase, but according to the app, the best practice is to draw a virtual wall in the floor plan. This is very easy and the robot adheres very precisely to guidelines such as no-go zones. It can orientate itself well in the room, so I wouldn't be afraid of stairs.

My stone floor feels comfortable. I use distilled water for the mop function and the limescale stains go away so well. Of course, the mop function remains rather superficial. However, I'm very happy in intensive mode. The suction function always works for me.