Maybe you should stop doing that, if it's leading you to say things like "I mean something like Christ set it up such that we're more likely to have a positive singularity".

Why?

Assuming that the other people you encounter inhabit the same reality as you — and I suspect you'll be able to find something about that to object to, but you know what I mean :P — what is subjective about it?

Existence is probably tied up with causal significance, and causal significance is tied up with individuals' local utility functions along with this more global probability thing. But around singularities where lots of utility is up for grabs it might be that the local utility differences override the global similarities of how existence works. I haven't thought about this carefully. Hence the question mark.

Knowing your decisions doesn't prevent you from being able to make them, for proper consequentialist reasons and not out of an obligation to preserve consistency. It's the responsibility of knowledge about your decisions to be correct, not of your decisions to anticipate that knowledge. The physical world "already" "knows" everyone's decisions, that doesn't break down anyone's ability to act.

On another note, I buy the typical compatibilist ideas about free will, but there's also this idea I was kicking around that I don't think is really very interesting but might be for some reason (pulled from a comment I made on Facebook):

"I don't know if it ultimately makes sense, but I sometimes think about the possibility of 'super' free will beyond compatibilist free willl, where you have a Turing oracle that humans can access but whose outputs they can't algorithmicly verify. The only way humans can perform hypercomputation is by having faith in the oracle. Since a Turing oracle is construbtable from Chaitin's constant and is thus the only truly random source of information in the universe, this would (at least on a pattern-match-y surface level) seem to supply some of the indeterminism sought by libertarians, while also letting humans transcend deterministic, i.e. computable, constraints in a way that looks like having more agency than would otherwise be possible. So in a universe without super free will no one would be able to perform hypercomputation 'cuz they wouldn't have access to an oracle. But much of this speculation comes from trying to rationalize why theologians would say 'if there were no God then there wouldn't be any free will'."

Implicit in this model is that universes where you can't do hypercomputation are significantly less significant than universes where you can, and so only with hypercomputation can you truly transcend the mundanity of a deterministic universe. But I don't think such a universe actually captures libertarians' intuitions about what is necessary for free will, so I doubt it's a useful model.

Note that I was pretty new to theology a year ago when I made this post so my thoughts are different and more subtle now.

To all three of your questions I think I hold the same views Aquinas would, even if I don't know quite what those views are.

on what mindware something non-physical would store all the information that is

How does Platonic mathstructure "store information" about the details of Platonic mathstructure? I think the question is the result of a confused metaphysic, but we don't yet have an alternative metaphysic to be confident in. Nonetheless I think one will be found via decision theory.

how omniscience settles with free-will (if you believe we have free will)

My answer is the same as Nesov's, and I think Aquinas answers the question beautifully: "Free-will is the cause of its own movement, because by his free-will man moves himself to act. But it does not of necessity belong to liberty that what is free should be the first cause of itself, as neither for one thing to be cause of another need it be the first cause. God, therefore, is the first cause, Who moves causes both natural and voluntary. And just as by moving natural causes He does not prevent their acts being natural, so by moving voluntary causes He does not deprive their actions of being voluntary: but rather is He the cause of this very thing in them; for He operates in each thing according to its own nature."

how omniscience interacts with the idea that this being could intervene (doing something different than it knows it's going to do)

I think my answer is the typical Thomistic answer, i.e. that God is actuality without potentiality, and that God cannot do something different than He knows He will do, as that would be logically impossible, and God cannot do what is logically impossible.

Theism is a claim about the existence of an entity (or entities) in the universe and also about the nature of the universe; how is that not a scientific question?

Because it might be impossible to falsify any predictions made (because we can't observe things outside the light cone, for instance), and science as a social institution is all about falsifying things.