1. Look up a local Real Estate school for class schedules, pricing, etc. Most states have a state-approved class with requirements regarding content and hours.
Maryland Real Estate Commission: http://www.dllr.state.md.us
Virginia Real Estate Commission: http://www.dpor.virginia.gov/boards/real-estate/
If you have a Maryland or Virginia license, you can get your DC license via reciprocity.
More info: http://www.asisvcs.com/publications/pdf/090902.pdf
2. Depends on the state, but you usually have to have a certain amount of experience in real estate, attend Broker classes, and pass a state exam.
3. Google local firms and set up interviews to see if they are a good fit and what they have to offer.
You'll have larger groups like REMAX and smaller firms. See which you prefer. If you want the brand recognition and resources of a large firm or the flexibility or smaller atmosphere of a small firm.
Look at mentoring, training, lead generating, etc. Ask about desk fees, commission splits, leads, resources, office hours, etc.
4. Talk to friends or family, ask during your firm interviews, or see who stands out to you in your area. I picked my first firm because I hit it off great with the Broker in Charge, trusted him and liked the way he did business. It was a smaller firm, but with enough local presence to bring in leads and carry some weight. If you ask questions in your interview and don't feel like they're going to spend time showing you the ropes, you may want to look elsewhere. Real Estate is a business you really learn out in the real world, so you'll have questions and want to have people around you who consider you a part of the team and are willing to help in the beginning.
5. You have to live and breathe this job to be successful. You make sacrifices and work hard, but if you put in the work and pay your dues, you can make a lot of money and find financial freedom. You may also want to look at commercial and business real estate if you think residential may not be fulfilling to you. Real Estate is not an easy profession or a "get rich quick" business, but you can make of it what you want if you're willing to do what it takes to make it happen.