If there's zero free will in there, why are we on this planet suffering so much?
I can answer that one, because I've heard the conclusions drawn from this supposition.
If God controls everything, then why does suffering exist? It exists because He wants it to happen. So if God wants us to suffer, that makes Him... well, kind of a jerk, to put it mildly. And is that really a deity that is worthy of worship?
If anything, that could be a good argument against the idea of predestination. The idea of God being a colossal jerk who likes watching His children suffering flies in the face of the concept of God being a loving and kind Heavenly Father. And I have seen some Christians try to justify this oddly dichotomous approach, typically with vague excuses about how we can't understand how God works.
Sadly, this approach actually turns people away from God and Christianity in general. It makes no logical sense, and as a result, does not serve as a good, logical reason to join a church or follow God. If you want to try to get people to join the church, you have to understand their mindset. If you want people to understand Christ and what He represented and stood for, you need to do so in a fashion that makes outsiders want to know more. Not give them further ammunition against His believers.
As far as how much He engineers our existence to produce certain outcomes, I surely don't know. It's not really my business at the moment, even if it's an interesting thought experiment. If He knows all possible outcomes, then it stands to reason He could put us down into the exact situation where we would definitely accept grace or definitely not accept grace. So why does He choose to put us where we are, in the time we live in, surrounded by the people and experiences we are going through? It's a real mystery in our current forms within this river of time. I fully expect it to be answered without a shadow of a doubt one day, it's just this moment is not yet that time.
The way I view it is this: God exists in an eternal, timeless state. In other words, he exists outside
of time. The reason why he knows the outcomes of our choices is in the same way we can pick up a history book and read about the life of George Washington. George certainly didn't know, with 100% certainty, what would be the outcome of his actions. But we can, because we exist outside his timeframe. And George certainly made his decisions without our interference, didn't he? Note that I am not saying that God is a time traveler or anything like that; it's just the best analogy I can come up with at this time.
God can see the decisions we make, the decisions we don't make, and the possible outcomes of all of them. He certainly doesn't control our actions. But if we pray to Him and ask Him for help, there is the possibility that He can help us. We have to have the humility to ask for His help, though. And if we are answering for help in making a decision or anything like that, we need to remain receptive to the answer He has for us - even if it isn't an answer we want to hear.