Take some tape and wrap it around the jaws of needle nosed pliers, to protect the leather, and use that to correct the way the bleed knot lays. They should look symmetrical. If you pull the bleed knots tight, all you need is a couple of stitches in the end tab, or a rivet to keep it in place. Also, if you keep the bleed knot close to the snap hook, you don't need stitching at all at that end. You really don't need to do anything with the tab, but it looks more finished if you tack it down. Veg tan works fine for leashes, but you need to condition it. I use a mixture of neetsfoot oil, parrifin and beeswax. Wipe it on well and let it soak in. Nice and soft and fairly water-resistant. Yours looks good for a first one!
Jeff