What I need to learn from here on in is how to digitize each former into FreeCAD - it's OUTLINE - so that I can join all the formers together to produce a 3D mesh that I can import into Cura...and print each section as a hollow tube according to the fore and aft former for each section of the fuselage.
As far as I know you will not be able to digitize the images (I have tried several different ways and failed every time), to keep you sanity you need to redraw them in FreeCAD, for arguments sake lets choose Sketcher Module as the tool to use (look at the example below, its only 3 sketches and the Loft tool).
Have you been able to create any of the cross-sections so far? To get started post a FreeCAD file that you are working on, so we take a look as to see where your stuck (it sounds like you are still in the drawing cross sections stage).
Once we get the envelope of the plane figured out than we can worry about the 3D print work flow.