THere is this thing on the upper right corner of the page, it is called a search function. Had you used it, you would have all your answers.
Rotaries? Not decided yet.
Multiple turbos? Yes
Twincharging? Not decided yet.
Custom tracks? Yes, you can check them on the test track section of the forums.
Why bother though, there is the top speed stat already, which gives the top speed of the car.