Printing everything on A3 is a nice idea. However, since the template will be (almost double the size) you may want to use thicker cardstock. Since you are going to a print shop, may I suggest that you have multiple copies printed out, so that you can raise panels and add greebles.
I am looking forward to seeing how a larger model of the Thunder Fighter will look.
Actually, the cockpit interiors (for both the two seater and QUAD) and landing gear can be found on Martin Saenger's site
www.paperaviation.de
With that being said, there are two versions for both cockpit styles. There is one that you can put a figure in (2.0) and one that you cannot (1.0).