I will try to answer you, but it may already be as precise as I can make it. We will see after you read my post. I want to acknowledge that I am not completely able to wrap my mind around what I believe the Bible teaches on this matter. I think it is much like the Holy Trinity in that respect. I believe Scripture teaches it, but I do not fully grasp it. I know that complicates my attempt to communicate, but I want to try. As far as my own knowing, where my understanding ends my faith begins, I suppose, it does stretch past my own limts to be sure.
1. God did declare to Hezekia that He would not recover, and I believe that God meant it, and I also believe that He knew it would not ultimately happen. I think these two things can coexist in God’s nature without making God a liar. The moment God declared that Hezekia would die, that was true. God wasn’t just pretending, or manipulating. It was true up until the moment Hezekia prayed. Do you think that Hezekia would have died had he not prayed? I do. It was a statement about his future, and God knew it was true. So did Hezekia, and that is why he wept so bitterly. God did know that Hezekia would pray, and that His prayer would be granted. It was in His (God's) Will. If it was not in His will, Hezekia would have not recovered. We see the opposite when Christ prayed, and asked God to allow the bitter cup of His wrath to pass from Him. It was not in God’s Holy Will to grant such a request, even though Christ’s sweat was as blood.
2. I believe that God’s Eternal Plan, Will, and Purpose, encapsulates and utilizes, Man’s sin, His momentary declarations and eternal decrees, Man’s prayers, His true, and Holy, attributes as they exist in His own Nature, Man’s limits concerning His own natural existence, God’s limitless power as He exists outside of His creation, His ability to grant, or not grant, prayers, His Holy Spirit, and so on. It basically contains all that happen. If God’s control, or knowledge of the future is limited, why does Christ instruct us to pray Thy Will be done on earth as it is in Heaven? What is this will that we are supposed to pray for, and is it less powerful if we do not pray it? I believe it is God’s Eternal Plan happening as He designed it to before time, and that nothing will stop it.
3. I believe that knowing all the future, or being able to control it, does not necessitate God a liar, but knowing only part of it, and not being able to control it, does. I believe that to be true in light of all Scripture. All-knowing, and All-powerful, are supported throughout.
4. I reject the idea of open-ness being needed to relate to God, and I believe that it is by His terms alone that come to Him. See my first post concerning the Gospel, and the state of our relationships before, and after, belief. Also note that self-denial relates greatly to this.
5. If you add a prequalifier to these verses, it should coincide with who God says He is. His Word should support the prequalifier throughout. God says in many places that He knows all the future, and that things are destined, and that people are destined. We see very detailed prophecy fulfilled, and more to come. You would have to add a lot of prequalifiers to God’s Word to make all of this fit in with the idea that God only knows part of the future, and only has partial control. It would require rewriting God’s Word.
6. God not being subject to His creation is the root problem with your argument. He is outside of time, and knowing the future, frankly, is a piece of cake for Him. Him not being subject to His creation has a huge bearing on what you are saying, because you are making Him subject to it by attemting to reduce His power (in your own mind) so that you can obtain a better understanding of Him, and relate to Him better. It does just the opposite, in fact, it is a deception, and makes God a liar. Christ died so that we could have a relationship with Him. Diminishing God's power makes the Gospel irrelevant. He is God, and we are not.
7. I do not believe that God can be fully comprehended. If God’s nature is supernatural, how are we as natural men going to be able to fully understand it? We want to, but never seem to be able to come up with a perfect explanation. How did Christ die for us before the world began, and also in a time frame of our world? I am resolved that much is beyond our understanding, and that to try and make it fit by changing God’s Word, is very sinful. It is a distortion. The more I know Him, the more I know I do not know much. This is cliche, but so true. We should be awestruck by God, and it should overwhelm our thoughts to try and think of who He is. I relate to God, as a believer, in Spirit and in Truth, not in a fleshly sinful mind. The Lord bless you.