That is some mighty big fins on that airplane.
As far as box modeling goes I use primarily the box primitive and extrude surfaces and ident (surface menu). I do not use divide because I could never get the hang of it and I don't like the way things subdivide after being divided. If I really need to divide a surface I usually use the knife tool.
You can use spheres to model but that's more traditional modeling rather than box-modeling which imo is what subdivision works best with.
The whole idea of box-modeling and subdivision, as I understand it, is to lessen the workload. Once you get the hang of it the subdivision routine does most of the rounding and smoothing work. Work you'd have to do manually using spheres and other organic shapes and manipulating the surfaces and vertices individually.
Subdivision won't do all the work. But once you get the hang of it you can design a basic shape made out of box type geometry and then subdivide it a couple of times until you see you have a shape you want to work with. Then you can undo and go back to the first level of subdivision and manipulate surfaces and vertices by hand, occaisionally subdividing again to check your work. Then when you are happy with what you have you can subdivide a final time. After that you have the option to manipulate surfaces and vertices again to finish the detail.
I think the whole purpose of subdivision is to save you time. Once you get the hang of it you can make a primitive box-model which subdivides into the shape you want. Thus saving you a lot of work. Then you can add detail manually. I'm sure subdivision is not good for every modeling task but so far I like it.