What are the conditions that must be met by the Imam, the preacher, or the one leading the prayer, and what is the ruling if one of these conditions is not met, and is it permissible to pray behind him?

Leading the Friday prayer and delivering the sermon requires the Imam and speaker to be Muslim, sane, male, adult (for those who prohibit the imamate of a non-adult), and just (for those who prohibit praying behind a fasiq/sinner). The Malikis stipulated, for the validity of the Friday prayer, that the Imam must be the same person as the speaker. The Shafi'is and Hanbalis explicitly stated the condition of masculinity for all sermons, because the Friday prayer is not obligatory upon women. The preponderant opinion is that whoever's prayer is valid for himself, it is valid for others to pray behind him. So, if the speaker is Muslim, his prayer and sermon are valid, even if he is known for sins, though it is preferable that righteous and good people be appointed.