What is the ruling on a minbar that is attached to the wall like a balcony, with its steps not visible to the worshippers? Does this affect the validity of the khutbah and the Friday prayer? And is there any difference of opinion on this matter?

The permissibility of the minbar (pulpit) for the Friday sermon is, by scholarly consensus, a recommended practice (mustahabb) because it allows the khateeb (preacher) to be seen and heard more effectively. The Prophet, peace and blessings be upon him, used to deliver sermons from the minbar, as narrated in the hadith of Sahl ibn Sa'd al-Sa'idi. If a minbar is unavailable, it is permissible to deliver the sermon from any elevated place, such as a mound or a cushion. Indeed, before acquiring a minbar, the Prophet, peace and blessings be upon him, delivered sermons from the ground. Islamic law does not specify a particular shape for the minbar, though the Prophet's minbar had three steps.