I have some questions regarding aerial combat since flying Zoics' wings are attached at the arms and not on the back. Does a flight check prevent the flyer from falling? And does the flight check then count as a separate combat action? If a flyer uses Throw or Missile Combat, do they loose any altitude in the process?
First, please allow me to deeply and humbly apologize for somehow having missed this particular question. With the coming of Covid-19, and thus the need to stay at home and refrain from going out and having the social life we are used to, one would imagine that would leave tons of spare time to do things like attend the Forum and be more careful concerning upkeep here. Instead, it's actually slowed down progress on our primary goal (completing the World Guide) and the distractions and concerns of this year feel like they've made it more difficult to deal with things like this Forum and other online media related to Shard... It makes no sense, but that's how it's gone for us, and we feel terrible that the result is an apparent slack in our duties here. We beg your forgiveness...
All that being said, you have asked some EXCELLENT questions concerning Aerial Combat! Let me see if I can answer them effectively.
* You asked: "Does a flight check prevent the flyer from falling?"... Essentially, yes. When engaging in aerial combat, if one is disrupted in a way that might make flight difficult (especially if their enemy is performing a specific action to make the character stop flying), I will ask the player to make a Flight roll to stay on the wing. In the cases where that Flight roll is essentially being used as a "defense" because their enemy "attacked" them to end their flight, then the character flying will need to expend Actions (as many as were used against them) to defend against that attempt to knock them out of the air. If, instead, it was some random event that could end their flight during combat (a high wind, a nearby explosion, falling debris, etc.) then I may ask them to make a Flight roll just to see if they stay in the air, but it won't cost them any Actions to do so... I apply this basic method to ANYTHING a character might be doing during combat that potentially gets disrupted in some way. Outside of combat, if something happens to disrupt a character's flight, I would require a quick Flight roll as well, just to make sure they stay airborne. If they had Keen Focus or some other Talent that might aid them in that activity, I'd allow the player to add those dice to the Flight Ability roll. Also remember, a successful Flight roll indicates not only that a character is successfully flying, but also that they are able to cover a certain distance while flying if they so desire. Any attempts to prevent them from doing so need to be carefully considered to determine if their enemy is even within range to be able to thwart their flight. During combat a character would need to make a Flight roll to initially begin flying if they weren't already prior to combat, and they would only need to use Actions to make another Flight roll if they have flown the full distance allowed based on their initial Flight roll's success. It works that way with ALL movement skills and abilities, for the most part. If they are just using Flight to remain above their opponents, but close enough to attack and be attacked using distance weapons, then they can continue doing that (within the limits indicated by the Flight Animal Ability) until they are exhausted, without needing to make further Flight rolls unless something is done to them to make them stop flying, or if repeated use of their arms to attack their foes causes them to lose altitude enough that they need to focus on flying again just to keep from descending to the ground (which gets us to your next question).
* You asked: "If a flyer uses Throw or Missile Combat, do they loose any altitude in the process?"... That's a VERY astute question,...and,...yes you absolutely do... At least, that's how I deal with it in my games. When flying characters in my game are flying or hovering above their enemies in combat, or engaging them in the air,...any time they have to use their arms to draw/attack with a weapon (i.e. each time they roll the dice to perform a single or Bundled attack) I let them know that they lose about 10-feet of altitude. I tell them to imagine that they are able to basically "cup" their wings for a moment as they hold themselves still enough in the air to throw or fire their weapon, or even engage an aerial foe in a burst of hand-to-hand combat,...but doing so means they lose a bit of altitude. If they haven't indicated how high the first intended to be, then I might roll a d6 or two to let them know they happened to be that many ten-foot increments off the ground at that moment (so rolling a "5" would mean that they're approximately 50-feet high when they chose to attack).... Successful or not, after the attempted attack they'd now be 40-feet off the ground due to lost altitude, and any further attacks during that same Round would decrease their current altitude even further! They're not "plummeting", mind you,...merely swiftly floating downward, but enough to make them take 1d6 falling damage if they don't expend an Action to continue flying while regaining altitude before they touch ground.
These aren't "hard rules" really, and if you as GM want to handle it slightly differently, please feel free to. That's just how I like to handle it, as supported by the basic way our rules work, and me having encountered the situation enough time to decide to make a ruling on it for our games.
Hopefully this helps!