I don't know for certain. But often in such manhwas, the availability of empty rooms can vary depending on the plot and setting. You could start reading it to discover if there is one.
It's hard to say. Sometimes the layout and availability of rooms can vary depending on the plot and settings of the manhwa. You'd better read it carefully to get the answer.
It's hard to say. Different manhwa have different scenarios. Sometimes there might be an empty room, sometimes not. You could check the latest chapters for a clear answer.
It's hard to say. Maybe you can check some fan forums or discussions for more specific info. But usually, it depends on the plot and the author's creativity.