Well omniscience is all knowing and omnipotence is all powerful. If a being is all knowing, then frankly nothing you do is unknown before it happens, therefore it isn't free will at all, but a script in someone being's head.
And that script is not enforced, its not even reveal to us, individually, we don't know where we're going to end up. So really you're free to do what you want.
since God knows everything that will occur, why in the world let billions live and die an eternal death, according to christianity, when he knows who will serve him and be with him eternally in heaven? Why not just create those few and not subject the other few billion humans and whoever else it's created to an eternity of torment?
Even, if ones were to spend eternity of torment, for the time that they lived, it was good.
That is not the workings of a compassionate and caring god. If I'm a parent and I know 100% absolutely positively that the child I'm going to father will be a child molester, rapist, murderer, and any other terrible thing you can think of, and in the end be put into a never ending sentence of torture by the state, would I allow that child to be born? No.
That's understandable. However God isn't bound by evil. To those that refused his care and compassion, never ending torture is inevitable.
A God that knows that I would not follow its beliefs, i.e. believing in it as the ultimate god that I should worship, should have never allowed me or any of the other billions of humans who don't believe, and have not believed throughout the ages, live in the first place.
To not subject us to an eternity of torment for simply choosing to not worship it. That would be compassionate would it not? If anything, torturing all those lives for choosing not to worship that god seems petty. "Oh you don't want to worship me? You don't want to acknowledge me as head honcho? You're gunna burn!"
That God still created us and the world we live in and everything in it, for us not to give thanks, that's not compassionate.
Also is injusticed to judge people on things that they haven't committed. God is not just loves, compassion and caring, God is also justice.
You said you wouldn't allowed a rapist to be born, that's giving judgement to things they haven't done. God isn't bound by time, but humans are. We can not be judge on things that we haven't done, we cannot be judge through God's ability to see the future. That's why Final Judgement comes at the end of time, and not at the beginning.
To make all those who doesn't want to worship God, not to exist from the beginning would be injusticed.