Personally? I wouldn't like white. Plain crystal or AB, maybe, but only with contrasting colors so it doesn't look kiddie or prom dress. That's a really PINK pink. If you didn't want to do other colors I would try to find either the closest possible pink that matches the dress or the un-foiled rhinestones that pick up the color of whatever fabric's underneath.
Again, personally, I wouldn't do a belt on that. The long points of the seam mean a belt would just be hacking you in half or shorter, depending on where your waist is. DEFINITELY the wrist cuffs on the floats, and maybe if you want to start small the 'tabs' around the neckline could be stoned over completely and then if at all possible (hard to say without seeing the material) the straps over the shoulders and across the back. It might be interesting to use very tiny stones to scatter-stone the skirt (they'd need to be tiny to not weigh it down) but that will take a lot of time to do.