The easiest and yet toughest way I've found to beat an addiction is to find something more addicting and less harmful. This is tough because it takes forever to find something of the sort, but it's somewhat easy from there on out, as your new addiction normally keeps you from your old addiction.
Yes, people do it all of the time, sometimes you just need medical help to do it. For example often alcoholics and drug addicts need to get into a program or recovery center and seek counseling. Some people quit just by going to support groups like AA or NA. It just depends on the addiction as to what kind of help you will need. BTW AA and NA are free programs and are available just about everywhere.
Yes, but it's in many ways. You can check Sherry's way or you can have a situation that will make you determined and passionate to end your addiction. My grandfather quit smoking in a week going cold turkey for his growing children.
There are many ways to beat addictions, but no one-fits-all solution. If I was on such a quest I'd research the addiction, negative impacts on the body, organs affected, what withdrawal symptoms to expect and so on, so the person seeking recovery knows what to expect and how best to navigate the journey. It's not usually easy but definitely worth the trip.
I found something new to do in its place. Then, instead of thinking about what you used to do, you are concentrating on a new hobby or interest. Oh and you can't hang around people who do what you used to do for several months minimum. Worked for me.