regarding shooting at friends, there is no penalty unless you actually down them
as for strafing, it's all about trying again and again, sometimes tenacity and luck play a big role... That leads me to a bug I discovered in the game way back when I played it on my original A500.... I completed the game with nothing but successful missions (I can tell you there was a particular trench strafing mission which took me days of continuous playing to complete successfully).... when you complete the last mission it was _always_ recorded as a failure no matter what.... now I call that a bug hehehe
ruining my perfect record even if I downed my one and only opponent!!