I've got all the C&C articles, and all of the other A-H references you have. I've done a fair bit of research into the D.I. The C&C articles don't mention armament because it was not consistent (for reasons given below).
It wasn't possible for pilots to change or specify the configuration of the guns because there were major differences in the airframe for the raised and "buried" guns. The fuselage for aircraft with the raised guns had cutouts which were not present on those with the buried guns, and also the gun butts were visible in the cockpit, whereas you cannot see them on planes with the buried guns. They came from the factory in the way the factory made them.
In general terms, there were three different types of armament configuration:
- Single Schwarzlose with no synchronization fitted over the top wing and angled to fire over the propellor. This wasn't popular with pilots (understandably).
- Twin synchronized Schwarzlose guns "buried" deep inside in the cockpit. Again, these were unpopular because it was difficult to clear the guns if they jammed.
- Twin synchronized Schwarzlose guns "raised" up to the pilot's eye level.
The very earliest aircraft had the single overwing gun, which was then replaced by the twin "buried" guns. Later aircraft had the raised guns, but production of the earlier style of fuselage for the "buried" guns continued and it's not possible to say what series of aircraft had what style of armament. The different series numbering related primarily to the engine rather than the armament or other configuration, or the date of production. Also, there were five different manufacturers of D.I aircraft and there could be variants within those.
Bottom line is that the only way to be sure of the armament configuration for any D.I is to find an original photograph of it. Given the references you have, you have a lot of the available pictures. You need to look at them to either see the scalloped cutouts in the fuselage for the raised gun versions. If you can't see the fuselage, you can look at where the blast tubes exit the radiator to see if it has raised or buried guns. If you can't see either, your guess is as good as mine. So if you have photographic evidence, that's all you need.
I will say that it is highly unlikely that aircraft with the early war finish (varnished fuselage and mottled wings or the hand applied streaking) had the raised guns. According to the Datafile special, the raised guns were first tested in January 1918 and were in general use after the summer of 1918, and by that time D.Is were being finished in painted lozenge or serrated bands. But never say never when A-H aircraft are concerned....