In order to make a 72 inch strip you would need to buy 2 yards.....36 X 2 = 72 inches. You would cut your strips from the length of the fabric (such as you would for sashing) ....not across the width.
Most cotton and cotton blend fabrics are suitable for quilting. Some use only 100% cotton. I am using up things I have in my stash and have used a lot of Poly/cotton blends to make quilts for charity.