Messerschmitt 109 Design Problems

[kaki3152]

Two points immediately jump out:
Why did Willi not redesign the wing to accomodate armament in later versions of the 109? If the Allied powers and Italy and the Japanese could design a fighter airplane wing that could accomodate armament, why not the Germans. I dare say that if the 109F/G/K wing had been redesigned , fewer German aviators would have died becuase of the inherent speed penalty in underwing guns.
Also, why did they not incorporate a starter? I bet the German mechanics would have applauded. Or would that have made them lazy?
Finally, I read somewhere that one version of the 109F had a cut off valve that would conderve coolant in case of a leak. This was only used in the 109F and not in later versions?