500E Doghouse.
The prototype 500E had the sides of the nose glazing filled-in so maybe the small windows just forward of the doors were added to give a little extra forward vision.
The horizontal surface on top of the doghouse was a modification Hughes engineers came up with for the various military versions of the 500 fitted with mast-mounted sights. The mast-mounted sight was found to be creating turbulence over the tail area. The flat surface helped to reduce the tail buffeting. The OH-6D and 500 MD TOW/MMS helicopters were the first machines to get this modification. It appears the designers at Hughes decided to add it to the 500E because it looked good! There was no aerodynamic requirement for it. It isn't fitted to current production 500Es and 530FFs,
500 Fan.