Yes, you do it every day. 16:8 fasting is basically just restricting your eating to two meals within those 8 hours, and is usually a long-term habit.
(and 4.) If you want to lose weight at any age, you need a caloric deficit. If you’re a girl, restricting calories will affect you less at 16, but if you’re a boy, you still have a lot of growing to do. Restricting calories will invariably affect growth, but can be mitigated with a smaller deficit and making sure to get all the necessary nutrition.
Yes, restricting your calories through intermittent fasting (IF) will help you lose weight. But your current BMI is ~22 and although they tend to be lower for adolescents, you’re hardly overweight.
Answered above.
No, being at a caloric deficit will mean you have less energy. On the other hand, if you do have some pounds to lose, that would help you.
You will likely get fewer calories than needed for maintenance, which is why IF is used for weight loss. If you want to know how to count calories, it’s easy to learn if you just search on Google, but many people do IF because they don’t want the hassle of counting.
I would wait with dieting until you’re done growing, since you’re not obese or anything. But if you have any other questions; shoot.