It's difficult to break habits but not impossible. But to cure all bad habits with one over-all solution will not work in my opinion. But for everything you need the will to change something and the power of endurance. To stop biting nails you can use chewing gum or just add an oil onto the nails (there are some made for this concerns). It's bitter and tastes bad and you won't want to bite your nails again. To stop procrastination I would recommend using the method "getting things done".