Are c-sections difficult if a woman is overweight?

Yes. Women who are overweight have a higher chance of infections, pneumonis, and blood clots in the legs or lungs with c-sections. If you are overweight and you eat right and exercise everyday throughout the pregnancy, you may keep your weight gain to a minimum which would be beneficial for you and the baby.
Yes but. All abdominal surgery is more difficult if a person is overweight. That said, it's done every day. Body mass index in the 30s is pretty routine. Once you start talking 40-50, it gets a bit more difficult.