There are several different versions of the Reiki principles, Five Precepts or Reiki Ideals as they are also known. All of the versions are valid and none is better than any other.
Being a Reiki Master is of course more than just three days training. In reality, it is the work of a lifetime, rather than just the attainment of a title.
“The act of laying hands on the human or animal body to comfort and relieve pain is as old as instinct.