My thoughts are as follows. The Kammback or a boat tail will be essential for getting your cd down. The biggest area for cd improvement is always at the rear of the car. Hitting all of the low hanging fruit will be good though. The less concave the front end is, the better. Because that will (iirc) create a high pressure area. As far as the splitter/airdam goes, the splitter will add downforce. The airdam only keeps extra air from getting under the car, but the belly pan + lowering the car should negate this. For #6 I will refer you to the rear end of the
Audi R10 TDI. The kammback works on the principle that with sharp edges the air keeps flowing rather than detatching and becoming turbulent. Which brings us back to the kammback. Sorry if I am stating the obvious or if I got anything wrong. But I'm sure I will be corrected if I did.
