[Just want to point out off the bat that I'm not trying to be argumentative and I'm really enjoying this discussion.]
I agree with almost all of what you're saying, especially the part about subjective reality. I believe in objective reality. However, as humans we are
incapable of perceiving absolute objective reality. How we understand the world is simply a mental construct, a model our brain makes in an effort to understand our sensations. Everything is put through the "filter" of human understanding.
An analogy would be like a computer. Computers, at their most basic level, understand nothing more than 0s and 1s. That's it. That's all they can handle. However, by building together streams of 0s and 1s and assigning them meaning in some way, we can get our computer to approximately represent complex things like images, videos, etc. It seems like anything can be represented in a computer, but that's just not true. Computers are actually finite state machines. It would be possible, given enough time, to go through every possible state your computer could possibly contain. So, your computer approximates these things, but there are a fundamentally limited number of concepts your computer can represent.
Sorry for the tangent, let's swing back to the previous discussion a bit.
Does god have free will? I think of God as a being with a deeper fundamental understanding of the laws which govern our universe and the ability to affect them. It's kinda like flying. Flying is not a defiance of the law of gravity, it is working with other laws of physics that allow you to overcome gravity, but to someone without understanding of any of the laws, you are doing something you ought not be able to do.
The reasoning behind the question of humans having free will is that, if everything is bound by natural laws, then theoretically if you knew the laws that govern the universe and you were given the exact position and velocity of every particle in existence, you could potentially calculate exactly how every particle would act for all of history. So the question is, are our thoughts and actions our own choice, or simply predetermined by their previous state, going all the way back to the beginning of the universe?
Now if a god exists solely in our physical universe, but as a more advanced being, he/she/it is presumably subject to the same governing laws. Maybe he has found a way to bend or change laws that we thought were immutable. But, being solely in the observable physical universe, the way in which god does so must be bound by its own physical laws. So we see, are the actions of this super powerful being simply predetermined by its previous state, which in turn is determined by its previous state, all the way back to the beginning of the universe? Does god have free will?
You see, it's actually the same question as whether humans do. Is our consciousness purely a function of the physical laws of the universe and its initial state, or is there some other part of us not governed by physics? Science, by definition, cannot tell us the answer. Science can get us closer and closer to understanding the fundamental laws of the universe. But it can't answer any questions about what is beyond them.