As you can see pants and "blouse" parts are pure black. That's because they use different texture. I believe it will enable us to make CA wearable on eg. Vault Suit or other stuff.
That's the idea, but not with the combat armor, I think it is like an uniform, and the clothing should be locked. Recently I separated armor clothing into another layer, and added 2 extra clothing layers. That makes the clothing you chose for your character to override the regular clothes of the armor. But of course, it can be deactivated. In that case, all armors would have their own clothing, just like in the original sprites. However, this is not implemented totally, and I have to change all this from console commands.
That black outfit is actually a missing texture, it renders black in my pc. But you can see how it would look with black pants.
And your clothing layer stays the same when you die, because it is just a value inside the character data.