Regarding point 1): To my knowledge the radiator and cockpit drag has a stronger influence since the very last official patch version. I do not have the feeling that it has a lot of effect - but enough reason for me to always manage the radiators and to keep the cockpit closed. Beside the aspect that an open cockpit wouldn't look good on a 109...
No idea about point 2). I am not flying Hurricanes and Spitfires - only sneaking up on their 6...
