If I remember correctly, Luther was rejected by the Catholic Church....he was removed from that church; ex-communicated..it was not HE that wanted to leave Catholicism.
Luther's teachings were rejected, as they were novel and erroneous. He rejected the Church and her teachings in favor of his own new doctrines and theology.
I don't want this to turn into a thread on Luther, but just to tie it back to the OP, Luther (and his progeny) will tell you they accept the Nicene Creed and as many as seven of the fist Councils of the Catholic Church. Yet I have demonstrated this is not true, as even the very first Council, that of Nicea, taught things all rejected by Protestants, such as the priesthood, celibacy, Apostolic succession via the episcopacy, the Eucharistic sacrifice, etc.
I agree with everything else you've said except for the comments on Mary...I respect her and love her...but the CC is getting very close to declaring her a co-redemptrix.
The CC is nowhere near close to declaring Mary as the co-redemptrix. Here is Pope Benedict...
"I do not think there will be any compliance with this demand [to declare Mary as the Co-redemptrix], which in the meantime is being supported several million people, within the foreseeable future. The response of the Congregation for the Doctrine of the Faith is, broadly that what is signified by this already better expressed in other titles of Mary, while the formula 'Co-redemptrix' departs to too great an extent from the language of Scripture and of the Fathers and therefore gives rise to misunderstandings.
"What is true here? Well, it is true that Christ does not remain outside us or to one side of us, but builds a profound and new community with us. Everything that is his becomes ours, and everything that is ours he has taken upon himself, so that it become his: this great exchange is the actual content of redemption, the removal of limitations from our self and its extension into the community with God. Because Mary is the prototype of the Church as such and is, so to say, the Church in person, this being 'with' is realized in her in exemplary fashion. But this 'with' must not lead us to forget the 'first' of Christ. Everything comes from him as the Letter to the Ephesians and the Letter to the Colossians, in particular, tell us; Mary too, is everything that she is through him.
"The word 'Co-redemptrix' would obscure this origin. A correct intention is being expressed in the wrong way. For matters of faith, continuity of terminology with the language of Scripture and that of the Fathers is itself an essential element; it is improper simply to manipulate language."
- Peter Seewald,
God and the World, pg. 306