I've just finished adjusting the exhaust and intake valves on my 1981 240D after removing the engine fan, the fan shroud and rotating the crankshaft from above (using a long breaker bar). I used the regular 14 mm wrenches and managed to adjust all 8 valves successfully. It's not really difficult to adjust them with regular wrenches.
LarryBible: on my 240D, if I did not remove the fan, it would be almost impossible to access the 27mm crankshaft bolt from above because the fan hinders the breaker bar, and accessing it from below would require the removal of the fan shroud (which in turn requires the removal of the fan).
For the manual transmission fill plug question, I just want to get everything ready before crawling under a car, especially dirty diesel ones :-)