There are some one million+ combinations of food arrangements I could eat tonight. I haven't picked one yet. God already knows which one I am going to pick.
If you flip a (fair) coin a billion times, the arrangement of possible outcomes (i.e., the set of possible sequences of outcomes of a billion fair coin tosses) is astronomical. If we assume that such tosses are random, we can nonetheless determine the probability of all of them and ensure that a particular outcome will occur.
Imagine I assert a that the result of a billion fair coin tosses will be some particular sequence (some exact result). Either my claim is true, or false. If it is true, then necessarily the result will be the sequence I claimed. If false, then necessarily it will be a particular sequence which differs in a particular way from that which I predicted.
My claim cannot possibly cause any particular sequence. Yet necessarily it is either true or false, and either way the outcome is determined.
Except, of course, for the fact that my claim is not causally efficacious. THAT what I said is true or false does not MAKE what happens true or false.
Likewise, knowledge of the future does not CAUSE the future (at least not necessarily).
The one thing God already knows I'm going to have, or any of the 999,999+ other options I could have had if I had so chose to do so?
You cannot have chosen that which was determined by definition. Therein lies the fallacy of this standard, common argument-type (i.e., "If God/Allah/etc., knew I was going to choose X, then...."). I cannot choose that which is determined, so to ask this question assumes it makes no sense.
So because he exists outside space and time, this resolves all the logical contradictions of a supposed God?
I'm not sure which logical contradictions you refer to, but existing outside spacetime is akin to the "block universe" or "tense" in that outcomes can be "known" from some reference frame or be true by definition
a priori yet be chosen (self-determined).
Why would I care about a God that has absolutely no effect on our dimension?
Interesting question. The classical deists (such as Newton) practically invented science in order to show that such an entity existed (the watchmaker, who sets the cosmos in motion but then has no effect upon it). Modern physics provides a myriad of possible answers, in that causation outside of our experienced dimension can occur via numerous mechanics, in including the structure of the cosmos itself. Thus there are a variety of mechanisms for something that doesn't exist in our dimension to influence it.