Is it permissible to sit leaning against a wall with my face not towards the Qiblah during the Friday sermon? And is it true that the sermon takes the place of two Rak'ahs and therefore necessitates facing the Qiblah?

It is disliked for a person to sit with their back to the Qiblah, facing the people, and with the Khatib to their right or left. It is not haram (definition) according to the majority of scholars, though some have deemed it haram. The proof for it being recommended (mustahabb) is what Ibn Majah narrated from Adi bin Thabit, from his father, from his grandfather, who said: "When the Prophet, peace and blessings be upon him, stood on the minbar, his Companions would face him with their faces."