I seriously believe that it is wrong to advise anyone that hacking is good or bad. Ethical or unethical - Hacking does mean breaking into a system. So it depends upon you and your interests. Considering that cyber security is a serious concern, hacking is very much a profession more so ethical hacking. Now you should decide whether you want to do it. Contact known ethical hackers and write to them. They can advise better on the pros and cons. However there is no known course, rules and guidelines so again the demarcation between good bad and ugly is blurred. Please think carefully and write to some known experts before you take it up. 

Yes , it's good to do

At the beginning time , you need to work hard very much and try to understand the basics clearly as well as nook and corner
Because networking is a vast area to study

When you become an expert in ethical hacking, after only you make money .

If  you are a beginner in hacking means , do whatever under an expertise advice.