You pay 20 cents per listing. Each listing is good for 4 months, then it expires, and you can renew the listing at 20 cents for another 4 months.
You also pay Etsy fees when you item sells. 3.5% of the product price.
No the fees are for each item listed and the fee lasts for 120 days per item. If you put a quantity of 2 then you will be charges .40 cents if you put 3 then it is .60 cents, but the listing will last for 120 days.