How can I make my belly flat with exercise but without making my face thin?

Not sure if possible. Make sure you exercise at least 90 minutes a day, don't skip meals, avoid soda, juice, dairy, alcohol and fried foods. Eat a healthy well balanced diet! also water, organic vegetable broth, green leafy vegetables, natural pickles, apples are great to fill you up so you dont feel hungry and they are very low in calories.
Difficult to do. With all weight loss and reduction of fat, the face loses it first, not the butt and thighs :(. Cosmetic physicians often say to maintain the last 10lbs for wrinkle reduction. I personally think you should get rid of the last 10lbs and just use a filler. They last up to 12-15 months. Patients who like the way they look take better care of themselves.