I join my borders with a straight seam. As for quilting I do a crosshatch all over the quilt using wide painters tape as my guide. Lay a piece of tape diagonally across the center of your quilt and use the tape as your guide. Then move the tape along the quilt lines. When you finished the lines you lay the tape perpendicular and quilt in the other direction. Tallgrass Prairie Studio: Straight Line Quilting...Hints and Tips