Stitch in the ditch is a good option but I prefer shadow quilting--quilting 1/8 to 1/4 inch from the ditch. It is much easier and faster, especially if you are using a walking foot. Definitely quilt the border. It could easily be done with a couple of rows of straight stitches, about an inch apart. The border gets the most wear and tear. It needs quilting for strength.
You can use chalk to mark a section. It rubs off easily but only use white, not coloured. Some coloured chalks will stain your fabric.