Is it fine to remove the world-writable permission for /dev/stdin ?

Issue

• Is it fine to remove the world-writable permission for /dev/stdin ?

• What are the below files used for ?

  /dev/XOR 
  /dev/full 
  /dev/log 
  /dev/null 
  /dev/ptmx 
  /dev/random 
  /dev/zero 
  /var/run/acpid.socket 
  /var/run/dbus/system_bus_socket