I use a series one ecu on my series2 without problems, you are correct in saying the knock sensor will no longer be in use. Alot of tuners say that the series one ecu is there prefered ecu, but i dont know why. As for the turbo as far as i am aware alot of people run them without being water cooled inorder to reduce the overall engine temps however i dont know how reliable or safe that is but i am sure you will have more replys soon.