Questions on Selling for the First Time

I’ve decided to part ways with my Lego mini figure collection that I’ve had since I was a kid. I have a rare figure that has a crack on the side of the torso. I was considering buying a new torso to increase in the condition of the figure. The range of the figure on bricklink is $300-$1200. Majority of the lower listings state pretty big defects like cracks whereas the higher listings are still used but have minor defects like slight fading. 1) Is it against the rules/unethical in any way to...