Hey Andy,
I can't answer too many of your questions, except one. To twin plug you will need everything you mentioned and a splitter from andial. There was a thread on here a while ago where Loren was leading everyone around on how to build a splitter for the signal, but I never saw the conclusion of the thread.
And here is a company that does turbo charged carreras.
http://www.geocities.com/protomotive/products.html
BTW we are neighbors.
Good luck and hope to see you on the road someday.
Rich