Hi Jane, the stitch is just a straight stitch with the free motion foot (darning foot) attached. So I can move in any direction. I don't have a stitch regulator so my lengths may be inconsistent.
I think the glistening is from the flash more than anything, in natural light it's transparent. I am using monofilament thread from sulkey.
I just stitch in the ditch of the sashing, nothing else (except the borders, since those are quilted with the backing they go through all layers). Since the batting is adhered to the top with the first quilting on the blocks, I wouldn't "think" it wouldn't need much more for the backing but I could be wrong there. Honestly, most of my quilts are wall quilts so are put through too much actual use, so I don't have much data on how well this holds up through a washing or something.