Some Questions about character class regarding rotation of camera and skeletal mesh

I have been following third person tutorial By epic games

and i am confused how did they made the player model(skeletal mesh) and the camera boom’s rotation independent. i will divide my questions for convenience

  1. If they uncheck use rotation from controller in the pawn’s settings then why does camera rotate by using addcontrolleryawinput (by mouseX event), if rotation from controller is disabled for whole pawn then why only camera rotated and not the other components.
  2. If we check the orient rotation to movement i.e.rotate the character including all components to movement direction then why doesn’t camera also rotate in that direction, it remains independent of that and only rotates with mouseX and mouseY inputs which i mentioned in first point.

I’ve searched UE answer hub for relevant questions but couldn’t find any, is there any docs page that explains all about character class functions or perhaps any dev can clarify about these, any help will be appreciated ,
thanks