It was not Osiris who judged the dead; but Anubis who weighed the heart and soul against the feather of Ma'at.

Osiris, lord of the dead. His green skin symbolizes re-birth. God of the afterlife; husband of Isis and father of Horus.

Osiris was Isis' husband (in the Ennead).

You are correct on the following basis. It was believed that when a pharaoh died they became 'Osiris' king of the dead and that the new pharaoh became 'Horus' the god of the heavens and protector of the sun god.

the cult of osiris ended when Osiris died