Read around the forums and the blog posts a bit more. A lot of your questions can be answered by reading the stickied posts in most subforums.
You do not need to live on just dividends. You can sell stock as well to generate income.
Given that you're young and you have a moderate income, your first steps should not be figuring out where to invest. Number one, you need to track your expenses and figure out how to live a fulfilling life while cutting out your excess consumerism. Doing that will have a far greater effect on your future than any investment strategy.
Second, given that you're young and have moderate income, your investments should be focused on yourself. When necessary, spend money and time increasing your career prospects, which should lead to higher paying jobs.
For investing, go to the Inverstor Alley subform and read the stickied posts. Max out your 401k match. Put $5,500 a year in an IRA. Buy low cost index funds and never sell them.
If you follow the general advice you find here, you'll be in great shape.