to add a skill to a unit, you just insert the skill's id into the field where skills go in a unit's classlist entry (you'll have to edit ModLibrary.cs if you're going to be using a modded character)
the "current.skills.Remove(122)" parts are there to handle the stat changes a unit has depending on its current stomach capacity (there's no current function to clear it all out at once, so it just does it manually)
the 50 and 130 values are chateau's struggle and stun stat amounts respectively; the public class defined at the bottom of Class.cs tells you what to match the values to
the int you see are the arrays used by the game to tell what attacks / skills a unit may have; the first array is for attacks, the second one is for skills
you don't need to worry about the -99 since it's a separate skill for the stomach sizer system
to edit attack range, you have to edit / create an entry in AttackList.cs to your liking since they're all hard-coded to only work with what's included in an entry (so you can't change range purely from character skills / stats)
you are required to put the character's asset folder into the game's modded character folder if you want to use them, though do note that attempting to put stuff into ClassList.cs to get it to function won't work due to it requiring some extra stuff that's not as easy to modify (unity files) and the game will treat them as separately entire characters (which you don't want to happen)