I'm trying to create a prototype of a portable input device for a computer. The idea is that the input device allows the same input as a normal wireless pen tablet, but augmented with special features, which could (for example) open programs and switch between them.

Now our current idea is to use a second monitor to run our mockup interface on. So basically an application of some sort that has a rectangular part to serve as the pen input area and some buttons alongside it for the extra functionality.

Now my question, as I'm very new to this type of applications (and new to Mac in general). What kind of possibilities are there to get the above functionality?
Is it possible to open and interact with applications from a separate application?
Even more, is it possible to map the mouse input that I have in my application on the first monitor?

Hopefully one of you will have an idea. Thanks