I 'd like to stay on topic as to the prophecy about Jesus and other prophecies for that matter. but on the subject of God planning Adam's sin, why do you think he did? that would be a contradiction. God's 4 main qualities are Love, Justice, Wisdom and Power. and he is perfect in all these qualities. however, everything he does is governed by love. God is Love. would it be loving for God to do that? tell adam not to sin, then tempt him, knowing that he would sin and then punish him for what he did?
You see, some have said, why didn't God wipe out adam and eve and satan right then and start again? well, satan had challenged God. he was challenging him as to who has the right to rule, who is sovereign. is man better off without God or not? the angels were witnesses to the challenge. now, God could have wiped them out too. if he wanted to, he could have wiped everyone out and started again. no one would know what he did, if he didn't tell them...but he didn't. Like i said, God is perfect in Justice. the challenge was set. Let's see if man is better off without God. if he did wipe out everyone, it would go against God's own standards of justice. just as it says God CAN'T lie, so there is NO injustice with God.
So it's clear that although God has the ability to foresee everything, he is selective when choosing to do so. otherwise, why would he say that he desires none to be destroyed, if he already knows what everyone is going to do anyway/ look at his pleadings with the Jews, asking them to turn around from bad, not to do certain things. if he has predestined everything, there would be no Love on God's part for us, no way of proving our loyalty to him, no point in preaching, no point in doing God's will, no point in anything, as everything has been taken out of our hands and we are just puppets with no free will.
and that is why the world is in the state it's in. since the garden of eden man has been given free reign to prove if he can govern himself. has been able to? look at history.
there is only one way for man to live, and that is under God's rule. he is the one teaching us to benefit ourselves. do things his way and it will turn out for the better. Man has had thousands of years to try all sorts of governments and although some have been relatively successful, they have not been able solve all of mankinds problems. Even the bigger things such as growing old and dying. These are the promises of the bible. Revelation 21: 3,4. Gods kingdom is the only way out. Jesus is king of that kingdom. He said his kingdom is no part of this world. He told us to pray for it in the lords prayer. Daniel prophesied about it when explaining the image of nebuchadnezzars dream. The kingdom would shatter the image representing world powers, in the feet, the time were in now. And the kingdom, or government is real, and as prophesied, will stand to time indefinite. And it very close to stepping in. it is in the days of these kings, our time, that the image will be destroyed and now is the time for Gods kingdom to begin its rule.