As far as I know, yes. There are certain custom headgear (earrings and whatnot) that I have seen use other partitions, but I have not tested for decapitation issues.
So the texture problem is fixed? The object in the second picture must also be from here http://www.nexusmods.com/fallout4/mods/22431/? It's just a ground object to represent that outfit when dropped in the game world.
That sounds both horrific and hilarious. Screencaps if you have them, please. Did you use the version of the nif converter? I've had some minor issues with some armors, but that was fixed with v1.9 I think.