I have a box of organic whole wheat cous cous. The ingredients say: 100% Whole Wheat Durum Semolina".
Can I grind this with my home mill and make my own durum flour?
that it has already been steamed or cooked. You can mill it and use it as a flour, but it will act like a non-gluten flour in your bread dough.
First of all it is whole grain, so it can only make whole grain flour, which extra fancy durum is not, second, as Mini said most likely it has been precooked.