And, then I scrolled back and found some answers to your question ... I don't know how I missed them!
I forgot to tell you to pin baste and remove as quilting. It is a bummer to have to stop and remove the pins, but it is the only way you can ensure that your backing stays straight/level/not bunched up (kisses are what they are called if the back buckles and you quilted it together in places).
A walking foot is indeed good for stitching in the ditch ... the darning foot is for free motion quilting.