Can you autoclave 100% glycerol straight up to sterilize it? Will it result in caramelization or will it be fine? I am aware I can dissolve it in water and autoclave it but it would make things easier for me if I could have 100% sterilized glycerol.
Glycerol can perfectly withstand autoclaving. However, for practical purposes, I prefer to autoclave a 60 % (v/v) glycerol solution, prepared by weighing glycerol to avoid problems due to glycerol sticking to volumetric devices, because at 60% concentration, it is less viscous and much easier to pipet.
Unless some component of your solution is close to saturation, you could also prepare a more concentrated solution containing the other components and complete the volume to be added with a more diluted solution of glycerol. Again, 100% glycerol cannot be accurately pipetted or measured in a cylinder, because >20% of the volume will stick to the pipette or the cylinder.