Im considering leasing a car. I dont know anything about leasing and I have some questions.

1. Can you lease used cars so that its cheaper
2. Is there a down payment when you begin leasing. If yes, how much would it be for like leasing for 6 months for a $20,000 car
3. Were do you get a leased car.. like at a dealership?
4. How much does it cost to say lease a $20,000 new car on average about $220 right?
5. If you get into an accident what happens does insurance cover it?
6. If the car breaks, is the leased car covered by the warrenty?