I agree with Dave's comments above: formulate a plan for what you want to do, where you want the project to go, how much time/money you expect to invest, what your "phase II" plans on for future development, etc. This will help you stay focused and on track as the project goes along.

As for your design ideas and getting the engine going, that sounds like a good place to start to me. Keep us updated and show us pictures as you make progress. If you're gonna build it, don't be shy about showing it off!!