For all the queries, balanced diet is the best solution. If your meals contain good amount of fibre (from vegetables and salad), along with proteins (curd/dals/ non-vegetarian items) and carbohydrates ( cereals/ potato) your body metabolism increases so that you can lose your belly fats easily.
Ample vegetables, nuts and dairy will also help you get your nails strong.
Next Steps
For a glowing skin, do not opt for any sudden weight loss. Drink green tea 1cup in the evening. Have atleast one fruit a day.