Exercise and overall weight loss will help reduce the size of your thighs. Walking is good, and so is yoga. Aim for 30 minutes, 3X/week.
Be sure to eat plenty of veggies, lean protein, low/no fat dairy, etc.. Drink water instead of soda
You cannot. The fat deposits on the thighs are there for a reason. The body will not let go of these fat deposits until last, that is when you are nearly dead because of anorexia or you are a marathon runner.
The only way to get rid of them (and the main reason why we women have them) is while you are breastfeeding a baby. The enzymes that make you lactate are the only ones that can get the body to burn these special deposits, since these are there to nourish a baby.
Love your bum, it is what makes the main optical difference between us and men (besides the breasts). Without the female shape there is no way to seductively move your hips while walking and dancing.
What you can do, however is tighten the muscles and the skin by walking daily and massaging them with cream daily. Also great: aquajogging.