How to ensure eBay like payPal integration with my website?

[jambhool]

I want to have eBay like paypal integration onto my eCommerce website where

- Buyers can directly pay to sellers, buyers need not have paypal account

- Sellers gets paid immediately

- My website or seller can initiate refund

Please help me select proper product or guide me to proper developer tools

Thanks in advance!

Regards,

Abhilash