I've played SGE before, but only very casually, and am returning after a few years. One thing I am unclear on is whether or not I need to allocate colonists to military in order for my laser/flak cannons to fire. Any help is appreciated, thanks in advance!
Your defenses will always fire, even at 0 military. however, higher military increases how hard it is to destroy turrets and how fast they fire, most importantly it determines how fast solar cannon will shoot which is the key to a well defended colony. At zero defense it takes just one neg to destroy a laser/flak.
Bottom line is yes absolutely allocate colonists into military, try to get it full military or as close to as you can.