About the quilting. I would never leave a 12 to 15 inch area unquilted. You stand a chance of the batting bunching up on you when it's washed. Pick a pretty design that goes along with the theme of your quilt and put it in there. Or even some thing really simple. The bag that your batting was in should tell you how big of an area you can leave unquilted but I always heard that rule of thumb is no bigger than your fist. In other words 3-4 inches square. However some of the newer battings say that you can leave larger areas unquilted. If you no longer have the bag go to the manufactures web site, you should be able to find out there.