I don't have an answer for any of your other questions, and I'm not sure anyone else does either. I don't know why things happen the way they do. To ask that question, you might as well ask why God decided to create at all. We will never know the answer to that question here, and even if we did, we probably wouldn't understand it.
I will say this though, God has more faith in us, than we will ever have in him. The fact that we're all still here certainly makes that clear, at least as far as I'm concerned. If you really want to believe, then open your heart, humble yourself, and talk to him. He is always listening, while most of the times, we are not. Sometimes we need a good smack in the head to get our attention, so my advice to you is, if you are truly sincere, don't wait, do it now. He will answer you, but listen with your heart, and not your mind. Be, as a child, and know. All God wants, is for us to love him, and love has no basis in reason.
Christ told us what God is up to in parables. Like a farmer, God is growing a crop. Evil people are weeds mixed in with the crop, which is made up of good people who have repented and are producing good fruit. It’s self evident that this world is part of God’s plan, that it’s a necessary part of producing the crop that God wants. Otherwise, God would end the world now or would have never created it in the first place.
This is what is revealed to me. God wants a certain type of people, and God’s people are often strengthened by adversity. Think of the difference between tomatoes grown in a hot house and those grown in a garden exposed to the environment. Don’t garden tomatoes taste better? It’s vitally important to get right with God before the harvest, so that one is good fruit and not chaff.