The backstitching for garments is important because the fabrics and seams will get pulled and tugged on quite a bit, causing the seams to come undone if not back stitched. The many seams in pieced quilt tops are secured by all the cross seams, and then once again by the actual quilting itself. The quilting holds all the layers in place so there is no stress on the seams. I also stitch around the edge of the completed top....it secures all the seams and also helps prevent stretching/distortion of pieces while sandwiching/quilting.
Feel free to ask as many questions as you need....we have all been there, done that....it's how we learn!