Queenie Chan

Got very confused with the plot! 1) How come the 13 years boy once found his dead body would return to his original "face", but not Kim Joon?? 2) The dead boy's head was smashed and non-recognizable, was the boy whose parents were killed, but that boy should lost his hand (wearing his mom's ring), but the scene of the dead boy's body showed both hands! 3) Why on earth the police, as well as the male main character would allow a girl who has no proper training to run around catching bad guys? 4) Kim Joon was killed at 13 years old, why the grim reaper he turned into was a 30 something years old man??