Very important to have a walking foot if you want to do machine quilting in straight lines. It keeps the fabrics going through the machine at even rates so you don't get puckers/pleats on back of your quilt (of course, you still need to baste too!).
And yes, a 1/4" foot is good to have for piecing. It will be a good idea to do a test with it though when you get it, to cut 3 strips 1-1/2" and sew them together (they only need to be about 6" long) and then measure the middle strip. It should measure 1". If it doesn't, then you should sew a scant 1/4" if it measures less than 1", or make sure you are sewing with fabric to edge of foot and try test again.