OK: so - thoughts on airships.
They work very similar to the ones in the Eberron setting: they have enchanted attachment points for enslaved air elementals to grab and hold up the airship, and an enchanted ring that a fire elemental grabs onto to push it. These pusher rings are
always at the back, and
never around the middle, because they are basically on fire and will set alight anything they touch - and no one will allow that to be wrapped around the middle of a wooden ship!
So, if you do an
image search for Eberron airships, you can take any of them that has the "ring of fire" at the back of the ship to be an example of what is possible in my game.
From your Clan training you know a fair bit about the airships and in fact have been trailed on and in them a lot: usually there are two air elemental attachment points for each fire elemental attachment points. When they were first starting to be made by the Clan they did not worry about anything except making them work: so these early models show a bit more of a "steampunk" aesthetic: bare bones ironwork holding the air elemental attachment points in outriggers sticking out from the sides, and a iron framework holding and enclosing a wooden gondola, with another bunch of ironwork at the back holding the fire elemental attachment ring.
The more modern design covers the whole airship in a shaped wooden skin, which is smooth and mimics wings... - in fact the Clan's gnome artificers have stumbled onto the concept of aerodynamics and are using the wings to generate lift. Currently they are not sure why airships with shaped wings can lift more and go faster, but empirically they know which shapes work best and continue to experiment. As a result a lot of the newer airships look like the
flying wing kind of design, just with a honking great ring of fire at the back pushing them.
So all of the classes below can have examples of the original or modern design.
There are some broad classes of airships:
Scouts: 2 air elementals and 2 fire elementals; very fast but can only carry 10 medium sized beings, with 1 pilot. 3 heavy repeating crossbows and one ballista (DMG p255)
Cargo / destroyers: these are roughly the same size and most of the class can be converted from the cargo / civilian role to the military / destroyer role quite quickly: 6 air elementals and 3 fire elementals: 8 heavy repeating crossbows and 3 ballista. Capacity of 35 medium sized beings with a crew of 3.
Battleships: there are only 2 of these that you know of: 10 air elementals and 4 fire elementals: very strongly built and quite well armoured: capacity of 60 medium sized beings: 16 heavy repeating crossbows and 8 ballista. Crew of 5.
One reason the crew sizes is so small is that everyone who travels in them will be Clan trained on airship related skills: firing the cross bows, repelling boarders, cargo loading, damage control. The permanent crew is there as the resident experts and commanders. Also, they do not fly if they do not have enough passengers to man every gun.
The weapons on them are examples of taking RAW or "rules as written" and combing and extrapolating them but but not totally handwaving and creating a new magical system: tried that once and it got real old real quick!
The heavy repeating crossbows are basically masterwork items from the Clan gnomes and are "double" - they are 2 bows on top of each other, fired from a two handed grip like a mounted machine gun, with a trigger in the handle of each. Because they are masterwork items, and they are solidly mounted on the sides of the airships they incur no penalties for their double nature, and so offer a doubled rate of fire for no penalty.
They have an enchantment on them that casts 4 Unseen Servant spells when the weapon is used: 2 of them work on one cross bow each and recock it as soon as it is fired and the other 2 reload the crossbow from the quiver of Ehlonna (DMG p189) kept near the crossbow at all times. The quiver is loaded with mundane bolts in the largest compartment, alchemically enhanced bolts in the middle compartment and full-on enchanted bolts in the smallest.
All of this means that these crossbows can fire 2 shots every single round.
The ballistas work on a similar principle, except that they have 4 unseen servants just to cock the thing and 2 to ferry the ammunition: they can fire 1 shot per round.
You also know that the Clan makes extensive use of bags of holding, allowing them to transport a
lot of cargo even in the smaller airships, and that each airship has 1 emergency bag of holding which is completely full of emergency gear and supplies, and another full of ammunition, weapons, and armour.
You know that none of the magic on the ship - from piloting the thing to firing the weapons - will work without a Clanmark. When you trained it was on small scale training models that did not have this restriction.