Re skills necessary to starting a business: you can get a rough idea here http://www.sba.gov/content/entrepreneurship-you

in practical terms, the first thing you have to decide is how aggressive you plan to be in finding clients, especially given your part-time job and school responsibilities. You also should give a think to the fact that "I'll set up a business doing web design for people or business" occurs to many people in your position as well as those who decide to make a real profession of it. Will the competition for clients be such that, once you've run through your family and friends, finding "live" clients takes as much time as doing the work you were planning to do for them?

There's more, of course.