Yes, but. . . . Bleaching systems that don't use the blue light can work equally as well. Results can vary tremendously. Just because someone uses the 'blue light' does not justify the additional cost, if there is any, in my opinion.
May depend. Normally, it is the strength of the bleaching agent and how it is applied to determine the effectness of the bleaching process. There may be many types of the "blue lamp, " in terms of intensity. The amount of time in contact with the teeth also makes a difference.
Yes. Yes. The result varies from patient to patient. This is one of the best ways to lighten your teeth.
Yes. The procedure is quite successful. However, results vary between patients. Not all patients will atttain the dramatic results advertised. Your expectations must be realistic and your initial consult with your dentist will detail the advantages and disadvatages of the procedure.