And I am still surprised people still come here looking for my stuff, even after all these years.
Now, let's get down to business. I think you can still find the necessary tutorials to learn how to mod the game. The process is quiet easy when you have learned the necessary know-how.
It is however quiet difficult to either talk through, or to learn through text.
That will be one huge wall of text, think wall of China
You could always do what I did, learn by simply getting the necessary tools and diddle till something happens, for good or bad
There are others that could teach you, I was never good at teaching that sort of things. I get too stuck at details that may or not be necessary, or relevant.
As for the black textures, those turrets were quiet unpredictable. Sometimes they were textured, sometimes not. Guess weapons of war have feelings and moodswings too