Fokker F27 Exterior Inlets

[SkyPilotage]

In the picture below. I would love to know whether this is only for the purpose of an APU Inlet or Does it serve for other functions like Heat Exchanger Ram Air Inlets?
http://upload.wikimedia.org/wikipedia/commons/9/9d/Fokker_F27_APU_Inlet.jpg
I would also love to know where the Primary Heat Exchanger Inlets are on this plane?

http://upload.wikimedia.org/wikipedia/commons/3/3a/Rolls-Royce_Dart_Fokker_F_27.jpg
This is a picture of the Rolls Royce Dart Engines and was wondering about the need for those movable doors/openings? The Exhaust is pretty Visible. Not Sure though which are for cooling etc..

I would appreciate detailed answers or clear resources to the topic.
Thank you for your time.

[rigpiggy]

Been a number of years but the inlets at the rear are for the acm heat exchangers. the doors on the lower front are for external fire extinguishers. I would have to look up my old books for the rest. the guard on the inlet is a required part for paradrop kit