affiliate program using paypal

I would like to set up an affiliate program on my site. Affiliates will receive coupon codes to distribute for 10% off any of our products. Affiliates will get to choose (create) their own code. Affiliates will post this code on blogs, via email, or tell others in person. When a new customer orders using this code, the customer will receive a 10% discount and the affiliate will receive their payment immediately via paypal. Affiliates need to be provided with a way to set up their code AND to link their paypal accounts so they can receive instant payments. If the affiliate's customer returns the product,? system? must be set up to debit (take back) the affiliate's commission.