Your are correct about the need of a decent guide for the military, for both melee, and missile troops. The wiki does seem, to leave out important aspects, of utilizing the military somewhat, but least they try. Do well to volunteer their time.
In version .16, the military is not as bugged, as when it was first introduced.Still needs a little micromanaging, but that's one the thing that adds extra fun.
Basically, there are 2 stages in the military. The first is the militia, where dwarfs, when idle, can at least train basic survival skills. Stage two, is when you have extra labor, that you can start building squads to stand sentry duty, patrol, train.
The schedule inactive, helps to keep dwarfs from goofing off. The alerts, can usher them to safety, while your squads can rush to defensive positions. 1 important fact left out, from info about the squad menu, is if you do set an alert, on the military screen, assign that alert for every month. So if a zombie rhino lizard attacks, then on the Squad screen, you can assign the alert status for the specific squad you need. If the alert is not applied for that month, they will behave as if nothing is the matter.
Alerts take precedence over the Active/training schedule, and inactive schedule, thus the name Alert. Which really helps when Boopy the baby snatcher, and friends try to sneak in, while a squad is training, in the Active/Training schedule, or inactive schedule.
Just activate the alert,in the squad menu for this type of intrusion, and let Boopy, get a hammer in the mouth, for his sneakiness.