I would think about tying it just at the intersections of the blocks. I would use 2 or 3 strands of embroidery floss. First leave a tail on top, go down, back up, go down and back up and tie it, knotting it. For the batting, see if any of them call for 9-1/2" or so, especially the wool one. These quilts have lasted 100 years. I have a pillow that is like this and it is dated like 1905 or something. Mother had a pillow like the one I have and hers went to pieces. It is the type of silk used. I also have a wool one from WWII that has ribbons on it. It is quilted with very large stitches. It is really heavy but wool was heavy back then. I really like your quilt and I hope it lasts a long time. Be sure to date it on the front and the back. I love the colors and all the work you put into it.