Personally, I always try to avoid stitching across when I do stitch the buckle one. Some will say it doesn't matter, some swear that it does weaken the leather. And like most, I use snaps or Chicago screws so that when the buckle breaks, you can swap it out for a new one.
Second, and this is personal preference, but I always do an border 3/16" from the edge. I find it gives a more finished look than tooling right to the edge.