Some thoughts regarding the fire (I am an ex firefighter with post graduate studies in fire and explosion science).
This is speculation of course because fire behaviour can be difficult to determine from a few photos. But it seems to me that there may have been a relatively confined fire around the area where the wing connects to the fuselage which migrated upwards into the interior of the aircraft through opened up access areas. If there was ever an external pool fire it was relatively small and located between the undercarriages. I don't see much evidence of a large pool fire. A small pool fire may have been extinguished quickly by the firefighters. The fire was localised in intensity breaking thorugh the upper skin in the area of origination first but also migrating through the fuselage fore and aft before breaking through the upper skin areas there with remaining hot spots fore and aft. The larger burnt area at the rear can probably be atttributed to wind direction.
Hope this helps.