Those engines were laying around in huge masses, cheap and reliable because they were designed for civil purposes. BMW makes good money currently but i doubt they would have remanufactored a small 801 series. So yes, itīs easier to take these engines and adopt them to the fw airframe which makes only a difference of 5cm in length afair. Afaik a research institue (TU München?) was somehow involved in calculating the efficience this cooler layout, so it isnīt a try and error system. The original gap of the cooler is closed.
Afaik the engine has only a single supercharger stage, but i doubt the aircraft will be taken too often to high altitude.
oh, and the ailerons are much larger on WW2 fighter aircrafts than they appear in those photos, huh i was really impressed standing next to a "lonley" wing at Flugwerk 2 years ago.
niklas
