Thank you Penz

I like to do that. Just like with maths: when you explain it to someone else, you start understanding it better
Progress: the nose section is 'finished'. I had a few hassles with the roof, but the overall result is OK. I need to continue. Next on my planning was the centre section.

This section was occupied by the second pilot/gunner and the radio operator. It was made of wood and both wing spars crossed it. The upper part of this section was used by the crew and their equipment: the two crewmembers sat there, had their instruments but also wiring, control pushrods and control hydraulics were located there.
The lower part was in fact the bomb bay. The racks were installed at the spars.
Both parts were seperated by a floor, 'also serving as a walkway.'
Well, thanks the Aviodrome archives, I was able to discover some more data. This enabled me to make a scratchy start with the radio operator's station. This station consists of multiple devices, all installed with flexible bands.
The first work on the centre section, was adjusting the structure. After viewing a lot of photographs, I concluded the bulkheads were far to wide (cross-sectional height). On one photograph, it is visible that one bulkhead was reduced to accomodate the prop levers, as you can see below.
Just one more detail: I was wondering what the purpose of the two knobs behind the pilot's seat was. After thoroughly reading through all available documentation, they appear to be the primers. They're a bit inconvenient located though...