If you don’t want to use a needle and thread, you can try closing small holes with fusing powder. You can buy fusing powder online or from your local fabric store. Follow the directions on the package to seal up the hole(s).
Purchase a vice drill, which is a pencil-shaped vice with small drill bits. They are available in craft stores. You may need to purchase smaller drill bits if the hole...
It's best to use a sewing machine. A good, heavy duty, sewing machine is useful when working with denim, as the layers of fabric can get too thick to sew...
Yes, you can fill in holes or cracks with a filler cream. Afterwards, buff the leather out and apply a matching color dye or pigment to the affected area.