There is nothing you can do about cellulite. ;) It's just like any other fat; the only way to reduce it is overall body fat loss, and most of us will always have some. www.sparkpeople.com/resource/quizzes_quest
And the experts answer: www.sparkpeople.com/community/ask_the_expe
Sagging skin is a fact of lift; whether or not you lose it all depends on genetics, age, rate of weight loss, and other factors beyond your control. It will either snap back on its own, or it won't; you won't know until you're done.
There are no supplements nor creams that will help either. Save your money.