Are there any natural foods that can increase the amount of sperm produced? And how far down does the scrotum reach in an average adult?
As long as you are eating a good variety of foods, then you are getting plenty of nutrients to produce healthy sperm. While poor eating habits can decrease the amount of sperm you produce because there is a limit on the materials needed, there isn't anything you can eat to increase your sperm production beyond your natural capacity. As it is, you are producing about a 100,000 sperm cells each day if you are an average healthy male.
There is no "average" hang for the scrotum because it constantly varies in size to keep the testicles at the optimal temperature to produce sperm. If you are cold, it draws up to pull the testicles closer to the body for warmth. If you are hot, it expands to increase the cooling surface to keep the testicles cool.