Metroid is retarded, I have 10 GTX 1060 3GB happily mining Eth as we speak.....
3 of the cards are standalone on mini ITX mobos all running windows 10....
So yeah, I dont know what people are talking about but I can provide proof you CAN mine on windows at this time.
The amount of VRAM used aside from mining seems to depend on the installation... I have 4 rigs running Win10 and 1 running Win7 and no two of them use the same amount of VRAM. Windows being Windows, I suppose.