You should have some copper wire in the kit. Wrap it tightly around the parts to be soldered and use stay bright solder and flux. I did my first one with a big old heavy duty soldering iron and it worked just fine. The other two were done with a small hobby torch. Before soldering, mount the cabane pieces on the fuelage and check to make sure the bends are all right for alignment. If they are, I wrap the wire around the pieces and put a drop of CA to help hold them together and then carefully take it off the plane to solder it up. It's pretty simple.

Or you could make a jig like you are thinking.

You should have no problem soldering...as long as it flows through the pieces it'll be strong enough. The wing mount is glassed to the cabanes so you have that helping hold it all together, too.

Barnowl gave you a pretty good idea for the N struts. I'll probably do that on my next one (or an "I" strut)

First thing to do is cut all the printed wood pieces out (I always hate doing that )

Don