Wow.
I have actually accomplished a similar task utilizing several different methods. One of my favorite methods was to set up example test steps that was accessed from the groovy script, the request and assertions being placed into a controller request and then storing the results. This allows for easy maintenance work of your requests and helps to keep xml out of your code.
There is a lot of options for what you are attempting to accomplish but it depends greatly on how much time and effort you want to put into this project and whether or not it is worth it in the end. Understanding what you are attempting to accomplish was quite difficult but if you have any specific questions to SoapUI and groovy development (IE, How could I use a controller script to run and control the flow of my test cases) than you will likely get a much better, quicker answer.
