I found a site with some interesting midi programs. One program, called Sundog, creates midi from a seed source of more than 300 musical scales. There is also a section about home made controllers. You can find out more ++ HERE ++

I'm trying the Xotopad application. The designer came back to me within a few hours which was very impressive. He said it should manage midi cc commands and patch changes from my tablet/pc. Also stopping and starting songs. I suspect a lot more too in BIAB. I'm going to download the demo and give it a spin with BIAB.