Cockpit:
Eagle Dynamics\DCS World\Mods\aircraft\A-10C_2\Cockpit\Textures
Exterior:
Eagle Dynamics\DCS World\CoreMods\aircraft\A-10\Textures
Exterior normals are greenish because blue channel is black for some reason, while standard is to leave it white. I'm not sure how dcs engine handles blue channel, but it doesn't really matter.
Anyway, I agree with OP, lot of DCS textures contain additional channel of data that serves no purpose no matter how it's being compressed, and while we can fix it locally, IC makes life more difficult. Even worse, dds alpha channel cannot be sampled into rgb compression, it require its own set of data, so you end up with double bpp.
And please, please, please, do not ever use .jpg for textures.