Barb, your quilt is truly beautiful. Your fabrics are so carefully chosen, the rings just blend from one color into another.
Robin, you don't need to square up paper pieced blocks. They should retain exactly the shape of the original paper, and you just trim on the lines shown on that paper. I think Barb gave excellent advice. For this pattern I think I would make some copies of some of the papers and practice on some scrap fabric in order to perfect my sewing technique. It's not an easy pattern. Using a thinner thread helps me on paper piecing too.