Complete work on an existing ASP site & Amazon Integration

We have an existing, custom-build e-commerce site which extracts data from an existing , sql-based, point of sale system then uploads it to an access DB, from which the site reads. The is 100% built and functional. The scope of work revolves around three aspects: 1. Refining the existing site code to be more efficient and quicker for the end user. 2. Completing a 75% module which adds new functionality to the site, involving single and mass uploads from users, integrated into the existing inventory 3. Taking the existing site, which only focusing on one department of the store's inventory, and implementing it 3 more times for other departments, with very minor cosmetic and structural changes.