Alright, lemme see if I can answer these.

Originally posted by Neonlatios:

Ill simply consider this as a mod focused on hirelings.

Correct. Many of this mod's features are around Arena Mode and its Hirelings in particular.

Originally posted by Neonlatios:

I've gone to other discussions and saw that "Hero hireling" exists as a 1% chance of getting.

Correct. This refers to getting characters like Hank, Sanford, Deimos and Victor in your recruit pool. You'll know them when you see them.

Originally posted by Neonlatios:

Like the name coloring of some hirelings (Blue Gasoline Fiend, Massive, having an indigo colored name

The name list used for Hirelings in this mod was actually put together by NeoX in an old mod from before this game had workshop support. The coloured names don't actually mean anything - it typically just means that the name is a nod to a community member.

Originally posted by Neonlatios:

a green AI from sleepwalker level having absurd tactic at level 4, 56

That's actually due to them being a VR Training Buddy! Different Hireling types have different stats and attributes in this mod. In this case, the VR Training Buddy has triple their normal Tactics stat, but only half the Strength, Endurance and Dexterity that other Hirelings would have. They also regenerate three times as quickly, are twice as resistant to being Dizzied and have 50% more TAC-Defence, but deal 30% less damage with their attacks. They also have a little less health than a standard Hireling.

When you hire a character, you can check their armour inventory - in there, there will be a Hireling Support Kit that provides a set of passive buffs applying to all Hirelings, as well as an augment detailing their "origin" and what buffs and debuffs it provides.

Originally posted by Neonlatios:

Does dual class mean anything?

That's actually how it works in vanilla. Hirelings have a priority list of skills - most of their level-ups will go into their Skill Focus and some will go to their secondary skill. At higher levels, they will also distribute their skills across the tertiary as well, but they each have a Weak Skill that they will never put points into. The main change this mod makes to that system, alongside giving them a higher level cap, is making it so that you can see what their secondary skill is too, which makes it easier to find the guys that you want.

Originally posted by Neonlatios:

Is there a more in detailed guide that you've put somewhere?

Not yet.

Originally posted by Neonlatios:

Basically I'm unsure what the non mentionned features are from this workshop's description. "-Lots of Hireling changes"

In summary:
- You can now see what each Hireling's Secondary Skill is alongside their Skill Focus.
- Hirelings now have much more varied behaviours, and are far more competent in combat.
-- They also don't run out of ammo or reduce durability on melee weapons, and will dynamically swap between melee and ranged weapons depending on how far they are from their target.
- Each Hireling comes with its own "origin" that contributes to its stats and what it can do - check their armour inventory to learn more about each one.
- You can bring more Hirelings with you into missions.
- You can hire more Hirelings, period. They also have a sharply increased level cap, once you start upgrading the kitchen.
- "Hero" Hirelings exist now.
- Probably a few more things I don't remember off the top of my head as well.