I'd give your body a few weeks to re adjust itself. Let your uterus shrink back to size and let your down stairs heal up. You may cause damage by wearing one without being healed up first. The girdle could mess with the blood flow and cause you to take longer to heal or cause damage. I'd definatly wait
No problem, I would ask a Dr. For sure though. I only have understanding of anatomy from taking an EMT course (and a massage therapy course) but a Dr. Can give you a better guideline on it.
After my csection the hospital gave me a special stretchy bandage to wear. They recommended wearing it for about 3wks but I wore it for months because my tummy muscle separation was above average. Ask your dr what he would recommend.