Is my anger towards my father considered disobedience (ʿuqūq) given his estrangement from his family, his claim that they practice sorcery, his missing of Friday prayers, and his hanging of an amulet which he believes protected him from sorcery?

Anger that does not result in mistreatment of the parent is not considered an act of disobedience (ʿuqūq). Anger concerning the prohibitions of Allah is Islamically مطلوب (required). The parent should be advised gently and kindly regarding objectionable matters, and this advice should come from those close to him. As for your father preventing you from visiting his family, if there is a valid reason for it, then obedience to him is obligatory; otherwise, it is not. If a visit is not possible, kinship ties can be maintained through other means, such as phone calls.