It seems to me that you hold this passing world too highly. You are not doing your homework. You have quoted Psalm 157.9 which does not exist. It is Psalm 137.9 which says "Happy shall he be, that taketh and dasheth thy little ones against the stones. “The background is that the Psalmist is cursing the enemies of the Lord. He wants God to be glorified with the defeat of His enemies. It is generally held that the death of babies, who are not of an age of accountability, will be judged accordingly, and go to be with the Lord. That covers most of your objections which seems to be about children.
Now you talk about God hardening Pharaoh’s heart. Have you not read that before that, that Pharaoh hardened his own heart against the Israelites by putting the Israelites into hard labor in Egypt? God was merely using the decision that Pharaoh had already made for His glory.
You say that YHWH God is not a God of love. God gives you food and shelter and work. He gives you the ability to make your own decision as to where you want to spend eternity and Christ has made that available for us through His death. The fact is that the LORD God is a holy God and hates sin which afflicts you and me and this sick world where there is hate, murder and destruction. But God is merciful that He does not pour out His judgment and wrath on this present world. You must also understand this, you cannot refuse to believe in God, because He does not measure up to your imperfect standard. That is eternally dangerous. Compared to God, we know nothing at all.
The real problem for many people is that this is the God with whom we have to do. You cannot wish Him away. It is like standing on the railway tracks and wishing that the train wasn’t coming. You had better have another look at Jesus Christ our Lord.
Christ’s prophet. Certainty for eternity.