How should Spellcasting work in a Magitech Western Setting?

[LoA]

So I've been working on my fantasy/weird western Setting Montesuma. This time I actually have a solid premise for the setting. A magically advanced empire called the Casamian Empire discovered how to travel across different planes and dimensions. Eventually they began to set up colonies inside of other realms. Eventually the Empire fell into decline, and the civilizations that rose up in other realms fell to isolationism, and developed their own cultures. One realm known as Montesuma has a culture that developed a pseudo american western ethos. Alchemical guns are the primary weapon of choice in this realm, and magic is primarily used as a technology base rather than as a secret institution as it was back in the old days of the Casamian dominion. In the absence of the Casamians, i'm thinking either a federal monarchial system arose, or a loose confederate Republic rose up in Montesuma. It comprises of three large states with one being more of a territory rather than a state, but it's close enough. There are structured cities with law enforcement, however out in the wilds it's a different stories. Marauders and  gangs terrorize pioneer groups and small villages, railroads bring goods across the land, but train robbers are always lurking around, and to make things worse there are all kinds of untamed parts of the land with all kinds of horrors and nightmares lurking around in the darkness.

So my main question is this. How should spellcasters work in this world? If swords have been basically phased out by firearms, what purpose does a traditional wizard have in this world if it's cheaper to just buy a gun that shoots a fireball rather than train a spellcaster to use the spell? This is going off of the logic that Sparkletwist often uses. Rather than having a handful of people that can use magic to expert levels of proficiency, everyone can use a little bit of magic, and that creates an environment where there are plenty of workers to maintain magical wonders. This is the logic that the official setting Eberron kind of functions on as well.

So what roll does the wizard play if magic is everywhere? Professors of magic that have studied magic all of their lives? The true geniuses of their generation? And if magic is technology does that mean that the wizard is a fundementally different class from the traditional Wizard? Would I be better off just re flavoring the Gearhead class from Pure Steam (I have the book and have been dying to use more of it)?

Also how advanced should this civliization feel? I'm tempted to put airships in this, but I feel like Railroads and a telegraph system should really be about it as far as it goes.

[Gardening-Architcet]

If everyone  can use magic to some degree than your going to wind up with a world like Saga Frontier 2 where magic is ubiquitous and the inability to use it
is considered a disability.

In such a world a lot of the technological development is going to be centered around facilitating the use of magic,and filling in the gaps that magic can't economically.

Wizard or Mage would just be a title for the prodigies that are actually good at using magic.
For comparison, anyone barring disability can engage in athletics yet out of the population how many have the physicality to become professional athletes?
Out of those with the physicality f\how many have both the inclination and dedication?


In a world of guns and explosives what role do battle-mages have?
First they'd be Force Multipliers called in as special use troops and not the bulk of an army,t here roles would very greatly according to ability.
But those among them who were combatants instead of playing a logistics&support or espionage role would act as highly versatile artillery.



If much of the technological base is magical, then advancement will be heavily influenced by the ease at which enchanted items can be produced.
And what exactly magic can do in your world is going to be the biggest factor, if we assume the basic fantasy rpg power set as well as a fairly economical means
of enchantment then...

Your setting isn't going to be late 19th to early 20th centenary for very long, it have even skip from medieval directly to space faring.