Hi Eva Lou,
I've had a permanent ileo for 3 years and am happy to say that I've never been dehydrated or craved salt. I drink a normal amount of water (64 or so ounces/day) and have noticed that over time, the output from my ileo has gotten thicker, so my small intestine is absorbing more fluid than it did in the beginning.
I prefer to drink Smart Water, since it has electrolytes in it, and it tastes like plain water.
I had Crohn's in the rectum, so I wasn't a candidate for a j-pouch, but would have gotten one if I had the option. All in all, I'm very happy with my ileo, because I've been disease-free, medicine-free (and almost doctor-free) since surgery, which has been wonderful. :)