BMW changed its tune on the tranny's in 07 and now recommend 100,000 mile fluid change. Keep in mind while the GM transmission is different for post lci refresh its the same fluid dexron iv...some food for thought...
I change mine every 30k...but auto are like a box of chocolate...you never know what your going to get.
As for the electric fan, it comes out super easy once the air snorkel is removed. It's only like two clips that hold it in place.
For the cooling system for the m54 motor it is recommended to change water pump and thermostat at the same time as expansion tank. They are known problem areas. Some also like to replace radiator too so it's a 1 and done solution. I know with the e39 it was like clock work every 76k miles the cooling system would fail.