Skin and hair color are important. People with dark hair and light colored skin are the best candidates. This is because the laser can more easily distinguish between the skin and hair making it more effective. That is not to say that it only works in these cases. Different skin types require a different type of laser so you need to ask plenty of questions if you're not one of those described above.
Is laser removing unwanted hair painful? Yes...but you can handle it. Everyone responds to pain differently but it's no more painful that the snap of a rubber band. Topical anesthetics are often used to minimize any pain. If the pain is unbearable then most likely the laser operator has the settings wrong and is burning your skin!
Is laser hair removal permanent? The word permanent is open to interpretation. The FDA uses six years as the definition of permanent for laser hair removal. In reality, follow-up sessions every few years will be necessary to keep the hair from growing back. Laser hair removal is not forever but it's the best method out there and lasts significantly longer than waxing or shaving.
