Hoegarden -- If it were me, I would use your salt just as it is. I don't think there would be anything wrong with making it finer, but I'm not sure it would make much difference to me. The salt is not really abrasive in a salt bar, as it is in a scrub. If I rub the salt bar directly against my skin, I might feel a scratchy grain or two, but the salt grains dissolve pretty fast, so the surface of the bar stays fairly smooth. From my reading, some people do use a coarse salt and like it, but quite a few seem to like the normal fine-grained "table" salt best. The only caution I have read about is to NOT use is a Dead Sea salt, because the minerals in that salt will make the bar wet and nasty.
Ruthie -- I just wanted to try a milk soap, and cow's milk was what I had in the kitchen. I froze the milk briefly to a slushy consistency before adding the lye, and I also included the milk fat in my lye calculation. I liked how it worked out -- no unpleasant surprises or smells, and the color of the finished soap stayed light. Even though I hear goat's milk has more benefits it also is quite a bit more expensive for me. I always have fresh "cream line" (not homogenized) cow's milk from our local micro-dairy in my fridge, and I want to use it more in my soaps.