That's why a lot of people keep hard candies around for when they get that sugar craving. I know people who use "dum-dums" (small suckers in different flavors) to help in that area.
So far as the caffeine and nicotine go, I'll tell you what my doctor told me...one thing at a time. I've been a smoker for years, and when I was leaving rehab, my doctor mentioned that if I choose to stop smoking, to wait at until I have at least six months of sobriety under my belt because trying to stop two things at once only increases the chances of relapsing on both. Made sense to me.