Is a 400cc bike too much to start on?

A 400 CC bike is not a bad one to start out on unless you get one rigged for racing. Progressing from a smaller engine to a larger one is a good plan. As your riding skills increase, you are able to handle more bike under you. Honda Rebels, or Yamaha Virago's make good starter bikes. Both are reliable and let you lay down a good set of skills before you go to something else.