I believe that both of your are assuming that particles actually have a position. In actuality, what we call particles are a collection of fields that occupy all positions usually in a limited volume, all the time. So it is not a probability of where they are. Within a limited volume they are everywhere. And the volume is only limited by a threshold field strength. If we choose to make the threshold low enough, the limited volume becomes bigger and bigger.
Probability only comes into play when two or more such particles interact. Then the fields, or a portion of them must collapse down to Planck size in order for the particles to exchange energy.
Regarding free will, let me offer the example of spontaneous symmetry breaking as a possible mechanism. Take the formation of ice. When ice crystals nucleate, they pick a specific direction at random. It's not really at random, it's predetermined. Yet ice will nucleate in different directions at different points on the surface of the water. As the crystals grow they eventually encounter crystals growing from other points of nucleation. Then at the boundaries where the growing crystals meet, we get what are called defects. If the world were truly deterministic, then we should expect just one uniform crystal when ice forms. But what we get is a mixture of different symmetry breakings. Since all nucleation directios occur, we can say that the process is random, for random selection would yield the same result. So because of spontaneous symmetry breaking, where orientation of something is selected, seemingly at random, we end up with a structure that is as random as if its creation was truly random.
Now extrapolate this to the big bang where the unified field started with complete symmetry, it was completely uniform, and as energy fell as the universe expanded, the complete symmetry was spontaneously broken. So we immediately get randomness in the universe. As the unified field split into gravity and GUT, and GUT broke into strong fields and electroweak fields, and electroweak fields broke into electromagnetic fields and the weak nuclear field, almost entirely via spontaneous symmetry breaking, the universe became truly random.
So spontaneous symmetry breaking is like making a choice. Do we take the left hand road or the right hand road. Perhaps we can say that the choice was predetermined. But we can also say that it is the fundamental expression of free will. We make the choice most often using intelligence, which gives it an element of predetermination. But inanimate objects like ice make the choice at random. Free will pervades the entire uniuverse, all the way down. Whether it is truly free is an open question. But there is no question that what we call free will is fundamental to all symmetry breaking processes in the universe.