is it mandatory to change all the fluids,differentials and filters at 100k? or could i get away with just getting the oil change and micro filter done like usual?

If you haven't done so already, at a 100K you should replace all belts and hoses, flush and replace the radiator fluid, and re-charge your AC. Also change your spark plugs.

The e60 has a "sealed" transmission and differentials and claims that these fluids do not need to be replaced during the lifetime of the vehicle. However, most knowledgeable mechanics dispute this and can replace the fluid through the fill holes.