Add custom products to WooCommerce for WordPress

I need a plugin developed that will extend the WooCommerce plugin for WordPress. Your job is to identify the best way to do this, using proper actions and filters, and then create the plugin. This plugin allows users on a photography site to purchase photo products of pictures. This eCommerce site has pre-defined pricing for all of the products. We just need the system to understand that five different 5x7 photos are 5 different products. Here is the how the plugin should flow: i) User opens an attachment page, which displays the large version of a photo. ii) Under the Order tab of a drop down menu the user selects a product. For example 5x7 photo. iii) The plugin adds the 5x7 photo to the cart and displays the default thumbnail size on the checkout page. iv) If the photo does not have the proper dimensions, the user is prompted to crop the photo. The edited photo is saved in a post type called "custom_orders". v) The edited photo replaces the photo to be printed. If the user changes the size the process repeats, using the original photo as the source.