The skin
All parts except the lower legs, face, udder
Wool
White since the wool tends to be higher quality than the wool from a black sheep. Also white wool can be dyed a multitude of colours.
No. Not even black sheep.
The fleece is the wool that the sheep is covered in.
The wool once it has been shorn from the sheep.
Harvest wool
Its fleece.
yes
You can dye wool or sheep black with it.
The possessive form is 'the sheep's wool'.
Most sheep are white, but there are other colors. The second most common color is black. And white ones can have white OR black faces.