I can really relate to the 'big appetite'. I've always had one and have amazed people with how much I can pack away. One thing I've learned recently is that since protein is harder to digest it is very filling. So at first when you're trying to reign in your calories and not be (too) hungry, bump up your protein intake. A can or two of tuna packed in water is very satisfying. Also, the other key is the fiber. Fiber does the same thing in terms of keeping you feeling fuller for longer. Check out some high fiber foods and try to eat more of them as well.
As far as exercise, just make sure that if your doing a lot that you don't go too
low on your daily calories. It sounds strange, but in this regard it takes calories to burn calories. But the right calories, the timing of them, and the proper amounts (not going overboard).
You'll see. Once you start tracking your calories you won't believe how much you'll learn, how successful you'll be, and actually how much fun you'll have.