There are many ways to learn to code these days. From coding bootcamps like Flatiron School to online courses to totally free beginner resources. The best way to learn to code depends on many factors, but the most important one is you. See what course is best for you.
People working in the marketting/Engeneering department take about 150-300 megs each. (Cad graphics, Big format pictures, etc..)
I doubt any studies exist on this issue, because it can change alot depending on the type of organisation you are, or the internal policies of the corporation you are working for.