Suzaku's combat skills saving him aren't really the issue here.
I use the Arthur example because it's the most absurd. There are other incidents of Suzaku being saved by circumstance, or Suzaku having access to something just by circumstance, which have also been brought up.
Basically, all I see you saying is, "Lelouch shouldn't be as smart as he is." Well, I think it's a lot easier to believe someone is a gifted tactician than someone has godlike luck, over and over again.
Hey, you know one more recent absurd event that occured to me? How in the HELL did Suzaku survive the Euphinator massacre when the mechs started shooting at him while he was on foot and nowhere near his mech? They never did explain that, did they? He ran RIGHT IN FRONT OF A MECH THAT FIRED ITS GUN DIRECTLY AT HIM and he somehow survived that.
At least when Lelouch survives something like that, we get some sort of explanation as to how he did it.