I did some looking, and can't find any of the info on the archived fandom wiki, so I'll ask here:
Are there any cheat menus?
List of all vehicles
Any customizable armors? (or other armors than the ayo armors that function like power armors)
List of all firearms
Location of lethice's castle (mountain is split in 3, so I'm confused)
How to unlock all areas in the places menu
Can you actually learn blood magic?
Why were some of the violence scenes removed? (referencing drider axe "Legs get to it!" scene)
Cheat Menus: Public downloads? No.
Discord downloads? Yes. (Toggled in the settings menu)
Activating Debug Mode in settings will let you cheat a bit either way (cloning equipment items via continuously equipping them, using items without losing them including Ezekiel's whatever which gives +10 stats every use, bad end ignore, reveal/reroll encounter paths, etc.)
List of vehicles: Not really that important as to my knowledge they're all restricted to goblins/gremlins and all upgrades are shared between models. The default mech is bought from Lumi and a Giant Slayer mech is either in the High Mountains or Lethice's Castle I forget which... any others I can't remember where they were.
Customizable armors: I personally never went looking so I can't help you. A few can be blessed/corrupted though if that counts.
Firearms list: Talk to Gun Gobbo about inventory, hover over missing entries, go to the listed location then reroll the paths until Gun Parts is available. It's tedious but much easier than legit searching.
Castle: Unavailable until you completely the dungeon with the imp from the start of the game in the Deepwoods, which in turn is unavailable until you complete the Factory dungeon in the hills section of the mountains, which itself is unavailable until you talk to Marae the Goddess out on the lake (use the boat).
Places: Explore, as you level more are unlocked and then you can find the next sections while exploring.
Hills->Mountains->High Mountains
Once you have the first in a chain it's just a matter of levels and luck in exploration.
Blood Magic: It's locked behind a special class, trade three perk points for a super perk point and unlock it... or the Grey mage special class which gives worse bonuses in exchange for unrestricted spell learning.
Lack of Violence Scenes: Different preferences for this particular mod... though I can't recall if that scene was in vanilla or another mod.