You will burn more fat if you exercise longer at a lower intensity. If you're not going to work out hard and often, exercise is a waste of time.
Yoga is completely gentle and safe exercise.
If you exercise long and hard enough, you will always get the results you want. Exercise is one sure way to lose weight, stay away from strength training because you will bulk up. Water fitness programs are primarily for older people or exercisers with injuries. The health and fitness benefits of mind and body exercise, such as Tai Chi and Yoga are questionable. Overweight people are unlikely to benefit much from exercise.