These are very interesting questions, so we'll start with Chista's answer and then move to a more detailed out of character answer:

Chista's answer:

"Well, the average person will probably stick with a good dagger, maybe a short bow for hunting small game, or if they have the coin, a sturdy crossbow," Chista says. "A firearm is way outside the average person's price range, and even if they could afford it, having enough money to afford ammunition in sufficient quantity is a bit of a stretch." Chista crosses her arms. "Of course, one can steal such weapons, but the average person won't be in a position to swipe a pistol or ammo from one of the Guilds."

"There's also the Zhentarim's 'Black network,' but again, I don't see the average person risking life and limb dealing with them. Sure, they'll sell you anything, even a firearm, but they always collect on that debt, and it's not always in coin." Chista says. "Even the most ruthless bandit clans and gangs think twice about dealing with the Zhents, but that's why they're the top dog in the underworld."

"Now, as for what kinds of firearms are out there, there are a lot of different models and makes, so I'll stick with the different types. So... we have Revolvers, Breach Loading, lever action, bolt action rifles, semi-auto, and Mana firearms. Each has its own benefits and costs associated with them, but each is a powerful tool desired by lots of adventurers and mercenaries out in the Borderlands. Of course, the real trick is affording the ammo. The Guilds can only make so much smoke powder, and they are really picky on how much they hand out."

"As for myself, I carry a revolver my mother gifted me before I set off on my adventure, a real boon in the Borderlands, but I can only afford a handful of bullets for it. (Ammo is very expensive out here.) I don't let that stop me from using it though, I've seen too many adventurers hold on to a powerful tool but never use it in fear of running out. I advise using your best weapons to win quickly, and you won't suffer a long battle.

From the Author:

In terms of weapons in the borderlands and the broader setting as a whole, we are looking at a world where technology is a product of magic/alchemy and rediscovering lost technology rather than conventional scientific methods. So, while we have a medieval theme, we have a rather varied level of technology, with magic and alchemy amplifying 'traditional' things (such as plate armor and crossbows) and rushing other stuff into the field much sooner than anticipated (such as firearms and kevlar-like clothing for armor).

So we have swords, axes, halberds, bows, crossbows, pistols, rifles, staves, and wands all in the mix. This is a rule-of-cool thing, as I like my fantastical weapons, cool swords, and guns. Still, I do have an in-universe reason for this level of technology, which I'll share quickly:

First, the Shattered Realms (as I call this setting) is a post-apocalyptic fantasy, with the current setting taking place 1000 years later (kind of like the Wheel of Time setting). So, we have advanced tech hidden in the depths of the "Labyrinth" under the earth, which can help bypass certain technological development steps.

Second, Alchemy and magic help 'cheat' the scientific method, and both are much easier to 'control' by the powers that be in the setting. While individual inventors, alchemists, sorcerers, and mages exist, most learn their trade from the Guilds or Orders that govern each specific field of magic and alchemy. This also limits how much 'advanced' tech is out in the world, as only an alchemist can make gunpowder, for example.

Third, this is a post 'modern' world; all the easy-to-access resources are tapped out, meaning the world depends on Alchemy to morph one element into another to make things. Iron, for example, can still be found, but only in certain deposits, usually near where a 'star fall' (a meteor) struck the earth, or by scrapping the remains of the previous civilization found deep beneath the earth. Natural iron mines are rare and treasured resources worth fighting wars over now. Apply this to a host of other elements and materials, and you can see why alchemy is vital to society.

Take those three elements; we have a world where guns exist, but a blade is preferred due to accessibility and cost. You're average person won't be able to afford a gun, with peasants and serfs unable to afford much of anything. Still, a crossbow or dagger is easier to afford and can be made without the need of the Guilds. Thus, such weapons are usually found in the hands of mercenaries, adventurers, and those who have the funds or backing to have them. Of course, bandits and outlaws will steal and plunder such weapons whenever they can, but they often stick with blades and crossbows.

As for types of guns:
Revolvers are popular for those who can afford them, with revolver carbines having a spot in the world.

Breach-loading rolling block-style rifles are the most common type found in the Borderlands, often in the hands of adventurers and mercenaries. They hit hard but have a slow rate of fire.

Lever-action rifles, with their high ammo capacity and rapid fire, are all the rage on the market right now, but those features also make them very expensive.

The army favors the newer bolt action style over lever action for its rugged simplicity and hard-hitting nature.

Mana/Magi weapons are energy weapons that fire bolts of magic at their targets. These draw from small crystal cells full of mana. The upside is that when depleted, all one has to do is recharge the cell, though finding a means to do so can be challenging.

Artificers are always crafting/reverse generating odd marvels, ranging from steam-powered gattling guns to lightning rifles. These are usually one-of-a-kindions, not found on the market.