You wrote: First, does anything happen that is contrary to His will? If so, please define sovereign. Then please define evil.
Regarding God’s will, I would make this distinction. There is God’s sovereign will and his permissive will. Hence all that happens in time is part of his will—either his sovereign will or his permissive will. Evil, which is a privation of good, is permitted by God who in his goodness respects and honors our free will, even to allowing us to definitively reject his love and to choose Hell. God permits evil; he allows free rational creatures to disobey—it’s his permissive will. But by no means does he sovereignly will evil—this would be against his very nature as the all-perfect and good God.
I like how St. John of Damascus puts it in his Exposition on the Orthodox Faith: 
God in His goodness(3) brought what exists into being out of nothing, and has foreknowledge of what will exist in the future. If, therefore, they were not to exist in the future, they would neither be evil in the future nor would they be foreknown. For knowledge is of what exists and foreknowledge is of what will surely exist in the future. For simple being comes first and then good or evil being. But if the very existence of those, who through the goodness of God are in the future to exist, were to be prevented by the fact that they were to become evil of their own choice, evil would have prevailed over the goodness of God. Wherefore God makes all His works good, but each becomes of its own choice good or evil. (BOOK IV CHAPTER XXI).
In other words, the very fact that man can choose evil shows the goodness of God who, foreknowing that this or that man will choose evil, in his goodness he creates them just the same. Otherwise, if, foreseeing this or that man’s fall he were not to create them, then as St. John of Damascus says, “evil would have prevailed over the goodness of God” and God would not have created them.
Therefore, as you noted, God placed the tree, and the serpent in the Garden, knowing Adam and Eve would sin.
This is true. The omniscient God foreknows everything that will happen in time. But foreknowledge and predestination are not the same thing; and predetermination is another thing still.
Foreknowledge has to do with the intellect. God knows all because he is outside of time, above it. Just as I can look at a map of the U.S. and see New York and Los Angeles and Dallas all at once, because I am outside the map, I transcend the map and see the whole country from above; so too, God is outside of time, above and transcending it and can see the outcome of all events. This is foreknowledge. But it is not the same as predestination.
Predestination has to do with God’s will, his loving choice. He is free to predestine man or not (he is not obliged—he doesn’t owe anyone anything) and he allows for man’s free cooperation. Those who God foreknows will not cooperate he does not predestine to glory—he leaves them free, he doesn’t force them, he doesn’t send out armed brigades to coerce the prodigal sons to come to their senses, as you so brilliantly put it!
In our discussion it seems that you sometimes equate predestination with predetermination. Whereas God’s foreknowledge and his choice to predestine the elect to glory entirely respect and honor man’s free will, predetermination indicates that which is fixed and immutable in God’s plan. For example, it was predetermined that I exist. I had no say in the matter; I can’t cooperate in coming into existence because before my creation I don’t exist :)
St. John of Damascus is clear: We ought to understand(2) that while God knows all things beforehand, yet He does not predetermine all things(3). For He knows beforehand those things that are in our power, but He does not predetermine them. For it is not His will that there should be wickedness nor does He choose to compel virtue. So that predetermination is the work of the divine command based on fore-knowledge(4). But on the other hand God predetermines those things which are not within our power in accordance with His prescience. For already God in His prescience has prejudged all things in accordance with His goodness and justice. (BOOK II CHAPTER XXX)
You have frequently referred to a screenplay in speaking of God’s plan and our role in that plan. It is a limited analogy (that’s true of all analogies by their very nature). I’ll toss in a couple of thoughts. If we think of it more as a live act, instead of a recorded movie, I think the analogy is better. And let us say that parts of the play are sovereignly willed by God and that others are freely improvised within a fixed context, so in this play God allows improvisation (part of his permissive will). This is true of comedy plays, for example, where there is a certain amount of license on the part of the comedians, but the outline is already determined. It’s still an analogy, limited by its very nature, but at least it somewhat illustrates what is happening in the great drama of salvation where there are both dimensions—the sovereign, predetermined parts and the permissive, free parts. If all were predetermined and God controlled every act, we would be like the planets who have no say, or the animals who act based on instinct; but clearly, as you so beautifully noted, we are free to pray and weep for our sins.
At first the movie analogy was God and the movie (and we were part of the movie), but then you threw in a new dimension—we are the viewers of the movie. In this expanded analogy the movie is predetermined, but the response of the viewers is not. The viewers response does not affect the movie or its turnout, but it does affect its impact on their lives. So the end of the film is predetermined, but not the end of those who view the film. And here the analogy fails, because in this world the filmmaker cannot foreknow how the viewers will respond, much less predestine the viewers to some reward. Moreover, in the drama of salvation, we are not spectators, but players on the field freely cooperating or not as it unravels in our lives.
In the end, I looked up the Roman Catholic take on all of this and I think the Catechism of the Catholic Church has a sound synthesis.
1. God freely predestines the elect: God is love: Father, Son and Holy Spirit. God freely wills to communicate the glory of his blessed life. Such is the "plan of his loving kindness", conceived by the Father before the foundation of the world, in his beloved Son: "He destined us in love to be his sons" and "to be conformed to the image of his Son", through "the spirit of sonship".94 This plan is a "grace [which] was given to us in Christ Jesus before the ages began", stemming immediately from Trinitarian love.95 It unfolds in the work of creation, the whole history of salvation after the fall, and the missions of the Son and the Spirit, which are continued in the mission of the Church.96 (CCC #257)
2. Man is free to cooperate or not: To God, all moments of time are present in their immediacy. When therefore he establishes his eternal plan of "predestination", he includes in it each person's free response to his grace. (CCC #600)
The biblical teaching of St. John of Damascus and the Roman Catholic Church are in stark contrast with the Calvinistic notion of predestination: 
We say, then, that Scripture clearly proves this much, that God by his eternal and immutable counsel determined once for all those whom it was his pleasure one day to admit to salvation, and those whom, on the other hand, it was his pleasure to doom to destruction. John Calvin (Institutes of Christian Religion, Book 3, Chapter 21, Section 7) . For Calvin all is predetermined (and this is not what St. Paul means by predestination).
I’ll take a look at #115 later today (if my schedule permits) or perhaps tomorrow. As I said, you know how to pack a ping ;)