My reading of the bonuses from the facility in-game is that the combat bonus is only for defense armies on that planet. Does anyone build defense armies?
This is correct.I believe the damage modifier applies to any army trained on that planet. They pair well with the military academy.
Not entirely. Awakened Empires use other army types for defence too. The Xenophiles I took over yesterday usd Xenomorph-armies to defend their planets.And the other 5% are reaching Gene Warriors / Psi Troopers, who can (in stacks of 20) just waltz through every enemy planet regardless of fortification (especially since the AI never uses anything but stock defense/assault troops).