Well, I don't know about understanding "all" of Tradition and the magesterium. I certainly cannot make that claim, no matter my own insight. But, I find it interesting that, considering your criticism that a priest reads prayers from a book takes away from the heart of the matter. Is not the Bible a book? Yet did you not state that the Bible has everything you need? Consider that, in one sense, you are claiming to rest all your faith on a book, and yet you citicize a priest for using a book as reason for his faith lacking heart. How can this be, and could it then be possible that such may be true for a person who rests in the Bible alone? For where is the heart at when one is reading the Bible? Consider the last question and your answer may help enlighten to how the books of prayer in Christian tradition fit into the whole of revelation and our communion with God.
But you are partially right to criticize ritualism, but mainly wherein it has drifted into hollow ritualism that is either of overzealous superstition or has become merely mechanical "going through the motions." For such things do not focus on the true meaning and spirit animates both the liturgy and the sacraments. And that true meaning and spirit is that of Christ.
Everything is something you have to do, not a choice. How can someone be sincere when they have no choice?
Ah, I see. So you are wondering where free will fits into all this. Well, this relates back to the aspect of the "doubles." For you see, the aspect that being of service or having responsibilities hinders free will and freedom in general is one of those bad ideas that are close enough to be easily mistaken for the real thing. For indeed, having to do things like genuflect or to stand and kneel during a service does indeed seem to hinder freedom. However, free will has to do with choice in that one is free to choose to do or not to do something. And indeed, a person could choose not to "go through the motions." A person could even choose not to go to Church, nor even read the Bible. For all those choices would hinder a person's freedom, at least if we take the logic in those terms.
But you see, those that go to Church, read the Bible, and do all sorts of services for the Lord (or, maybe more imperfectly, out of fear of condemnation/want of salvation - that is, primarily for personal reasons, rather than in the fuller spirit of interaction and communion with God) are also acting out their free will by choosing to do these things. How we choose to use our free will ultimately has consequenses, both good and bad, depending on how we utilize our freedom. For as St. Paul notes:
Do you not know that if you present yourselves to anyone as obedient slaves, you are slaves of the one whom you obey, either of sin, which leads to death, or of obedience, which leads to righteousness? But thanks be to God that you, having once been slaves of sin, have become obedient from the heart to the form of teaching to which you were entrusted, and that you, having been set free from sin, have become slaves of righteousness. I am speaking in human terms because of your natural limitations. For just as you once presented your members as slaves to impurity and to greater and greater iniquity, so now present your members as slaves to righteousness for sanctification. When you were slaves of sin, you were free in regard to righteousness. So what advantage did you then get from the things of which you now are ashamed? The end of those things is death. But now that you have been freed from sin and enslaved to God, the advantage you get is sanctification. The end is eternal life. (Romans 6:16-22)
So therefore, the deceptive double of true freedom in which one is of service to God according to the righteousness of God is the false freedom in which one is of service to sin according to the iniquity of sin. When in service to sin, one may be, in a sense, "free." But this freedom's end result is death. However, our service to God is true freedom, and the end result is eternal life.
But ultimately, at least in regards to our own limitations, we cannot tell with absolute certainty who is being sincere or insincere in their faith. That is primarily to be judged by God. Yes, we are able to discern things - and such discernments can help us to consider what is true or false. The main part of this discernment has to due with what we have been taught about Christ, as St. John notes:
By this you know the Spirit of God: every spirit that confesses that Jesus Christ has come in the flesh is from God, and every spirit that does not confess Jesus is not from God. And this is the spirit of the antichrist, of which you have heard that it is coming; and now it is already in the world. (1 John 4:2-3)
So therefore, it is by what has been handed on to us and imparted by the Holy Spirit that helps us to discern. This discernment asks much of us (or so it can seem), but at its heart, the emphasis is in knowing that "God is love, and those who abide in love abide in God, and God abides in them" 1 John 4:16. But further, St. John notes:
Love has been perfected among us in this: that we may have boldness on the day of judgment, because as he is, so are we in this world. There is no fear in love, but perfect love casts out fear; for fear has to do with punishment, and whoever fears has not reached perfection in love. (1 John 4:17-18)
Hope this helps in some way.
Pax Tecum,
John