They also sell a product called "Fray Check". It is applied to the edge of the fabric to prevent fraying. I usually do the flat felled or a French seam. A French seam is sewn with the wrong side together in a 1/4" seam and the fold the seam in side and stitch again on the inside of the garment. This encloses the raw edges and gives the inside a finished look, too.
To add width to the front, cut to strip twice the width that you want to add - example need 12" overall, cut to 12" strips the length of the front. Seam them to the front, fold in half and stitch again. It will work like the front placket of your modern button front shirt. You will then have 6" on each side to balance the front.
Slash