i can help, i ponder the same.
1. God knew that to have true fellowship with creation like Himself - as persons, it had to have free will to genuinely choose to be with or reject, God. otherwise it’s not real.
2. giving someone the capacity to disobey, doesn’t mean you are responsible for their disobedience.
3. satan didn’t have jurisdiction until man fell.
4. satan is limited in what he can do. our current lives are a lot better than what we have earned. not only do we live under grace - God’s Riches At Christ’s Expense, we don’t suffer nearly as much as we deserve to.
5. as far as your plan questions are, ask why God would separate part of Himself and put all the punishment for sin every person ever did onto His son, for all sinful people, when not all people would decide to accept His sacrifice? the sins of billions of people and the associated punishment for trillions of sins. look at it from God’s perspective. consider the suffering put onto Christ in a few hours, trillions of sins.
the fact is for genuine fellowship and love, God had to create creation with free will, and this means the real ability to disobey and say no.
Nice!