unless we are thinking about different things, the flat needles are used for lacing (with leather lace) and conventional eyelet needles are used for thread. I use mostly harness needles but occasionally glover's needles and curved upholstery needles. Never tried silk thread for leather, I have always used waxed linen thread.

For burnishing edges, a smooth piece of plastic (such as a toothbrush handle) will do nearly the same job as a fancy dedicated leather working "burnishing bone".