you should be able to pull the therm housing off without removing the fan, but I have a fan removal wrench i bought specifically to remove e36 clutch fans. some people can get it off with a BIG, but THIN adjustable…but 90% of the time you need a wrench like mine, a friend currently has it but ill try to get it back so you can use it.
fuel filter is on the bottom of the car under the driver’s side foot well area, should be a big metal cover, remove the two 10 or 13mm bolts, pull it off, and you’ll know what to do from there
cabon filter is behind the glovebox, never done that
diff fluid is easy, if you have a 14mm allen socket it’s super easy.