[Plugin: WooCommerce – excelling eCommerce] Add to Cart with URL Query Strings?

Hi All,
I’ve got some commercial computer applications and I’d like to have WooCommerce handle user registration. The idea is a user clicks a button in the app and is taken directly to a WooCommerce checkout page with fields on the page pre-populated (and not editable) with data supplied by the application. Once payment is confirmed, a registration code is calculated using some of the application supplied data, and an email is sent to the user with the code.

I’ve figured out that the app can send the needed information via URL query strings, and also that I can use php to read this information. I’ve also worked out php functions for calculating the registration codes. However, I’m rookie with WordPress and a total newbie with WooCommerce and php. I pick this stuff pretty quickly, so I’m not looking for detailed steps on how to do this, but it’s a bit overwhelming and I would appreciate being pointed in the right direction. I’m assuming I’m going to have to do some editing in some of the php files, but I’m not really sure where to start.

Thanks in advance for any help.