RE: Speed of sound question. Need to settle a debate.
You can prevent the string jump if you place two large balls of cotton in the buck's ears prior to the shot. Of course, you'll have to be able to move faster than the speed of light, but if you can, you eliminate the problem of arrow speeds that are below the speed of sound.
E=mc2/light speed*3/kinetic energy of cotton ball placement/your age x your weight.