Buzzsaw,
To answer your questions about the V15a, yes its an E-1, but no, I do not think there was any meaningful difference between the E-1 and E-3 aerodynamically. Only the fitted armament was different. Now one of the test you have posted show that there was 0 to 1 kph "difference" between the MG FF being present or not.Other than that there was a slight bulge under the cannon drum in the underside of the wing. I do not know what drag that was responsible for, but I do have British tests for the Spitfire which give a speed difference of a whopping 1 mph for the similar bulge for the Hispano ammo drums...
As for the V15a test, the full paper has been transcribed on my site
http://kurfurst.org/Performance_test...w_109V15a.html
and I have also recently uploaded the originals to this forum, you can find in one of my recent postings in another thread.
As for the 3 papers you have posted, they are turn times and radii for the 109E at 0 and 6000m, at various flap settings.