Re: "#1. The Pope is preserved from error by the Holy Ghost whenever he speaks magisterially on matters of Faith and Morals. So such a situation would not arise."

Surely you misspoke Tridentinus?

The usual and V1 sanctioned expression is Whenever he speaks ex cathedra. Surely you are not intending to develop that doctrine from "ex cathedra" to "any only papal magisterial statement on matters of faith and morals"? Such as, for instance, Sacedotalis Ordinatio?