1. Magic. 2. Either magic or rebellion by Cardinals. 3. No, the people of Rome were not condemned when they followed an Aryan pope. Repealing continence would not be heresy and esoteric discussions on the nature of God are not really enough to condemn the entire Roman Church to Hell for the time its leaders were on the wrong side of a doctrinal dispute that was settled not because we were sure about the nature of Christ, but because we agreed on it in Council Heresy is reserved for matters of universal agreement, as you say, but not the discussions of natural law morality, although I seem to recall that Constantinople holds the teaching on Continence to be Anathema.