Sewing or "stitching" in the ditch means that your quilting is done right in the seam lines of the quilt. Meaning where ever two pieces of fabrics join it will be quilted where they meet
A scrappy quilt is done with random prints and colors. Comes from people using up their left over fabric- in the old days it was usually from fabric that was used in clothing cause people couldn't afford to waste anything or afford to buy bedding. Now a days it is mainly left over fabric from other quilts but could be from clothing. I have a few quiilts the we sit around and say - Grandma had an apron from that or I had pajamas from that. Keeps family history alive.