What are they made of?
Wood and metal are classical materials for ship construction, and most airships are made with these in mind. Usually, they are slightly sturdier than water ships, but war airships can be quite tough. (Remember, you're not invulnerable in a ship, so even an all dragonscale ship is still going to take damage.)
What's the most popular place lore wise where people purchase airships?
Karith is where most will purchase or rent personal or cargo airships. War airships are internationally illegal from a lore standpoint, so they can only be found and made off the grid.
What kind of weaponry can airships have?
Only war airships can have weaponry, and weaponry can either be what you would find on a war galley, specially designed spell "canons," or a combination of the two. Spells can be cast from spell "canons" if present up to a certain point, but remember that this is subjective to powerplaying. Eventually your ship will run out of mana and have to recharge, so just be mindful of that.
What kind of spells can we use?
Just like spells for your character, you must own spells before you can have your ship cast them for you. Also remember that only WAR airships can cast spells. Personal and cargo airships cannot.
Can we have handheld canons or use this technology elsewhere?
No. Absolutely not. You can read the official airship lore to find out why that is from a world standpoint, but the short version is that handheld spell canons or canons outside of war airships are a big NO and against the rules. Do not use them.
War airships say they have mages? How does that work?
Yes, each war airship comes with 10 mage NPCs as a crew, but, unlike the battle mage units in the mercenary shop, these mages are like those from the NPC shop. Therefore, they can only use spells and weapons that you own – beyond their starter kits, of course. This is to balance them out since war airships are already powerful.