Oscommerce Changes Required (contact form issue, buy now & install add on)

Three OsCommerce changes required: 1) Our 'contact us' form is not working, it says 'message sent' but we are not receiving any messages from it (have tried several emails), needs fixing asap. 2) The Add to cart 'action=buy_now' feature on the product results page does not add the item to the cart (it instead takes the user to the product listing page). This needs to be changed to allow the user to select a size and add the product to the cart from the product results page. 3) Install discount codes module (this one does everything I want - [login to view URL] but I couldn't get it to work). Please only bid if you speak fluent English so we can communicate effectively - thank you!