OS Commerce v. 2.3.3 - Install Coupon/Discount Module

We're looking to install a coupon module into a pre-existing installation of OS Commerce version 2.3.3. Other plugins have been installed. If possible, it would be nice to have a copy of all the changes inside a folder, or single document, so that I can know what was changed, should it need to be edited in the future. The project is not time sensitive, but good communication is required. If the module being installed offers MORE features than those listed below, that is perfectly fine. There are a few requirements: The coupons must be customizable by dollar and percentages. The coupons must be either unlimited, or one use per customer. Coupons can be restricted to: Specific categories Products Or used for the entire catalog.