RE: MUST use epoxy?
Yeah but to get wood glue to set up right and make the strongest possible joint you really need to clamp the joint. Fine if you're building a kit, but hard to do on an ARF. Consider than the Mosquito's main spar was built up wood, glued together with..... regular wood glue. Well, not REGULAR wood glue, but not epoxy. The Junkers company made an enormous flying wing glider in WW2, and it was all wood, all glued together...... my point is, you don't NEED epoxy to make a strong joint. But I'm not going to bet a plane on anything else.......
Andy