The City of Refuge

What is the significance of this city of refuge (or hope)? How is this city of a type of Christ Who is the refuge and hope of His people? What are the 2 immutable things of God? To Whom must a sinner flee for hope and refuge? Why was the only way to enter into this city was to have done something worthy of death? How must a sinner come to God? Why will the guilty ones receive complete acquittal? Why do people think that they can remove sin themselves? What happens to the sin of those who believe on Christ and His completed work at the cross? How is it that these sinners will come to Christ the God Man?