OS Commerce - Fix Coupon function, Install BuySafe, install Easy Checkout

We are running an OS Commerce eCommerce website. We need the following: 1. We have a customized single page checkout. This needs to be removed and in it's place install one of the OSC easy/fast checkout mods. We need to have on or during checkout process: - Coupon Field (Described Below) - BuySafe module installed (Described Below) - UPS and USPS based shipping modules - Order total including number of items in cart, discounts, sales tax and total price - Checkout Breadcrumb - Order comments - Default shipping to billing address with ability to change shipping address. Add note next to credit card field “Having your order shipped to a different address than your billing address may cause delays”. Right above billing address add the text “Please enter your billing information as it would appear on your credit card statement.” 2. Install BuySafe module on checkout page. 3. Our coupon function is not working. This needs to be fixed and added to the checkout page. Code must be written in PHP5. Please provide a list of any change made, includes files that have been altered.