4. Are the vital points only for doing damage to the human body?

... Absolutely not. Although the vital points are recognized as areas of vulnerability they are also points of healing and invigoration. It is thought that these points allow access to the flow of Ki energy.

Vital points for the application of techniques in the martial arts
can be seen to relate to meridians and chakras.

... It is important for us to remember that in Eastern philosophy and health practices, mind and body do not suffer from being thought of as completely distinct and different. Mind, body, and spirit are inextricably wound together when we consider the energy of ki. Moreover, the connection of the individual to the circular forces and elements at work in nature is part of this picture. These relationships are important to the study of martial arts and are revealed systematically as one’s training proceeds. By practicing the physical, and developing the connections between the conscious and unconscious, the mental and spiritual realities of this energy can begin to be understood. As the skills develop and experience grows, the ability to access and utilize these energies improves. At more advanced levels, the attention turns to ki as the primary concern of the practice, and physical technique becomes more of the consequence of the application of ki. The reaction becomes the action in this case.
... Martial artists understand practically and intuitively that there is more going on in their training than merely the physical. Knowing that the human body is so fragile that it can be easily been damaged should dispel any illusions of invincibility. When practicing, emphasis is on mutual respect and care for the training partner, and this consideration for others is extended outside the walls of the dojo.
... This ancient knowledge of ki is also of interest to martial artists for its own sake, with respect to personal healing, stress relief, and pain management, but also because of the relationship to vital points on the body that can be used for self-defense. There are many points which, if manipulated a certain way, can cause pleasant sensations and healing energies, but if struck or squeezed can cause pain, paralysis, or in some cases, serious injury and death. Throughout the centuries of studying these vital points, there have been various mappings, using drawings or statues, to illustrate the locations of meridians and points. Three-dimensional bronze sculptures were known to have been made as early as 1026 AD in China for the purpose of teaching acupuncture and moxibustion students.
... In different geographical areas and textual renderings, the same points and their connecting meridians sometimes have different names, presumably to control dissemination of this knowledge to ensure that it was used for appropriate purposes. Certainly acupuncturists are cautioned against the use of certain points, or specific points at certain times, because of the danger of causing injury. In addition, other points were kept as secrets within the ranks of physicians and scholars of the healing and martial arts. It is thought that this knowledge of striking vital points, along with their use in grappling, was introduced in Japan by a Chinese martial artist named Chen Gen Pin who arrived in 1638. His students formed separate schools of jujutsu incorporating these techniques.
... The study of vital points has captured great attention in Western martial arts literature because of the near magical powers this knowledge seems to impart to the practitioners. However, it is the use of ki energy, balancing and focus of power that pertains directly to the training process. From a health and fitness point of view, this where the real "magic" is, the area of the traditional wisdom that is of most value to modern students.
... Clearly, there are many targets available on the human body, where it is weak or where vital organs can be impacted. It is interesting that in Eastern martial arts, special attention has historically been paid to locations that can also heal, and often a strike at these points causes temporary reactions such as pain, paralysis, or unconsciousness without resulting in permanent harm. Knowledge of these points is extremely useful considering the "prime directive" of self-defense, that an opportunity to escape or immobilize an attack is always the preferred strategy. The more the martial artist learns about the areas of vulnerability of the human body, the more he becomes aware of having to protect them.