That's a really cute quilt, and the big sister hippo comment is adorable! I also would leave off the prairie points. Even though the batting says 10" I would quilt it a bit closer around the border just to control some of the puff (that would be my personal choice). I've seen lines, and they could be wavy lines, running perpendicular to the border, and there could be a few more lines in the wavier parts. The bartack thing described by Tartan would be cute too.