It is a common misconception that you can direct were you want the fat to come off your body by specific exercises. The truth is your body will lose the weight from where it wants to. Generally speaking, where you gained first...that is where you will lose it last. So don't worry about it and work the whole body. Under that flabby tummy those abs of steel are developing ready to be revealed in due time!
Do you mean by tummy droopiness, loose skin? That is depends on several things. Genetics, how long the skin has been stretched and age. Pray that you have the right parents, curse those kids for doing that to your tummy and lie about your age (that last one will not help one iota...but it will make you feel better about yourself)!
The only thing you can do to help is lose the weight slowly (giving the skin a chance to recover) and apply a good moisturiser.
I myself have loads of loose skin. I see it as an earnt badge of honour and a reminder to never go there again.