nice job on the DIY and I won't knock you for making it. I know they take a lot of work.
But I will mention that it's not necessarily the approved method to vent the cooling system which is why you may have experienced the cooling fan issue you mentioned.
GT1/ISIS/MoDiC = Factory authorized diagnostic system used by BMW dealerships across the world.
NCS Expert = BMW Factory R&D programming tool available on the internet (not intended for the public and not available to the dealership network)
OEM = Genuine BMW part only available from a franchised BMW dealership.
DME = Engine Management Computer