Many people like to start with questions like this one. Why is there a Hell? Well here is your answer.

God is a loving God, but why would he make hell if he loved us? Think of it this way. Take a person you love or are bonded with, let's say someone killed them. You go to the judge, he says he find a the murderer guilty, but since he is a loving judge, he let's him go. How would you feel? Mad? Yeah I would too. But that is why God made hell. He is loving, but also just. It isn't a love problem, it is that God has justice. And also, hell was not made for us in the first place. It was made for satan and his followers to be thrown into. So, I hope that answers your first question.

Why did God make sin?
He actually didn't, the original so  was by Adam and eve, they ate the apple on the tree when God told them not to. Why? Did God make this happen? No, satan persuaded eve to eat it. Why sin entered the world, many bad things were added. Death, pain, agony, sadness, illnesses, diseases, depression, and even ticks and mosquitoes.