[maecrispy]

You rarely ever need hot water assuming you're using a good deteregent. Warm water is fine. As far as getting your MF's (or any other laundry) soft, use vingar in the final rinse.

Your MF's get stiff and less soft because of the minerals in the water. The minerals get depositied on the fibers and make them stiffer and less able to absorb liquids. The vinegar, which is a mild acid, dissolves the minerals therefore restoring the fibers to their original state.