Copy-writing Website

I am launching a new internet-based copywriting service geared toward small to medium foreign companies that want to improve their English language websites, brochures, and advertisements. I need a clean looking site with different pages for services, team, contact and the ordering page. The ordering page is the tricky part. Customers will input different categories for word length, project completion, particular editor and coupon codes. The customer will then upload a word file of their documents and then pay by creditcard. As soon as the order is placed, the system will assign that order to a particular editor and send both parties a message. The message should contain a link to a forum where both can communicate back and forth until the project is completed. I need to integrate an e-commerce solution, preferably something easy to manage like OSCommerce or ZenCart with the messaging functionality of a ticket service. Looking to start ASAP.