Good questions. Any kind of thorough answer would be book length—several book lengths—so I’m going to try for a brief overview and link you to some more detailed resources.
The short answer is that none of the things you mention are doctrinal changes or inventions. It’s important to remember that when a Council or a pope defines a specific teaching, that teaching didn’t just show up overnight, or in a vacuum, or because some scholar in his cell decided it was a good idea. Historically, teachings have only been defined when what was commonly accepted and believed by the Church was challenged by heretics. They weren’t “invented” or “added” by the definition—they were supported and bolstered as long-standing truths.
This is especially important for understanding how the Trinity is described in the Creed (and the Immaculate Conception.) That part of the Creed was formulated to address a heretic who specifically denied that the Holy Spirit proceeded through the Father, but “filioque” was not un-thought or un-believed. See this, which includes citations from some Church Fathers, and this which addresses the question of Councils adding things to creeds.
Anyone who does even a little googling will quickly realize that there’s no lack of evidence about the Catholic position on all these issues—the hullaballo starts because everybody interprets the evidence differently.
Really all these questions come down to one: the nature of the pope’s authority (or primacy). What is it and how does it work? If it’s what Catholics say, then it explains the “whys” of all the other issues, and any good historian can explain the technical “how” of these issues coming about and being answered in the historical Church. So, if you really want to understand the Catholic position, my advice would be to read as widely and deeply as you can—from genuine, orthodox, actually-Catholic writers—about what we believe the pope’s authority to be and why that’s so. (The links below on the issue go wide and deep once you start clicking through.)
While we’re on the the papacy: let’s be very careful about the definition of Petrine infallibility. It doesn’t mean what most people think. Infallibility is a negative charism: because the Holy Spirit guides the Church, the Vicar of Christ cannot teach error in matters of faith and morals. It’s not a guarantee that the pope is holy, or perfect, or a good leader, or right about everything. In his person, he could be a sinner and a heretic (and we have had some pretty terrible popes.) But because the gates of hell cannot prevail against the Church, no matter how bad a man a pope may be, he is incapable of formally teaching error in on faith and morals in the name of Christ. See more, see more. And this article is long but very thorough.
Petrine primacy: The nature of the pope’s primacy as understood by Catholics has its roots not only in the whole of Scripture, but in the actions of the earliest popes and the writings of the Fathers. I’ve collected some resources in this tag (start about 5 pages back for the really relevant stuff.) These articles and these break the issue down by sub-question and type of evidence. And I strongly recommend Fortescue’s book The Early Papacy.
And in general, this website is really useful.
Now, concerning the New Mass:
I’m not going to make any friends for saying this, but here’s the basic truth: the Novus Ordo as implemented immediately after the Council was, by and large, an unholy disaster. And I don’t use the word “unholy” lightly. Grave abuses were committed and even institutionalized in popular feeling. However: the aesthetics, propriety, and “goodness” of the Novus Ordo liturgy—in both theory and practice—is a completely separate question from its validity. The Novus Ordo Mass is a valid Mass when said according to the rubrics by a validly ordained priest. Whether one believes it to be a valid mass or not depends on what one believes about the authority of Councils and the pope in regards to the liturgy, which of course hinges on the previous questions about authority.
Two final thoughts: a good resource is always the Catechism, searchable online here. Also important is something that’s often tricky to discuss and understand without confusion: the very important notion of the development of doctrine. See here, for starters. In a nutshell: it is not innovation, modernization, or corruption to explicate with a newly developed understanding a truth that has been present implicitly from the beginning. (If this wasn’t the case, Scriptural exegesis would be crippled, and Protestants would have a legitimate point when they use “But the Bible doesn’t say that!” as an argument against sacraments, the priesthood, etc.)
I hope this helps answer your questions. Please check out the links; it”s worth the time to become familiar with the historical evidence and why we interpret it the way we do.