Integrate PayPal adaptive payments into Wordpress installation

Hello, Im trying to build a marketpress with wordpress. Basically I alread have a custom post type for products, and each product post type will have some custom fields, like the price, the % commission to send to the vendor, the paypal email of the vendor and a shipping cost. When a visitor click buy this item it will pay via paypal and payment will be splitted to the main email address of the site administrator, and the email associated to the products. The visitor will also be able to add the product to a cart and pay only at the end of his navigation (check attachment as example): in this case we should pay attention because two products added to the cart could be associated to 2 different vendors (means that with the site administrator payment will be splitted in 3). Last, of course, there should be an OK and a KO pages for payments and there should be confirmation messages to the buyer, to the vendor and to the site administrator. I dont need webdesign or custom post type management. I only need the raw functions to make these things working.