I don't think you can make a reaction specific to a caste, only to an entity. I don't know about the rain or seeing things die, but I think the hard code is against that. Also, how would you determine which caste a redcap is if they are only distinguished by the color of their cap? They aren't born with caps, so would it just be their color preference? Also, as far as I know lathe's are primarily for metal cutting, and seem a bit too advanced for redcaps, try carver's den or something similarly shoddily sounding. Also, are we planning on making the flower people a wee folk? Because if not I might just make them for myself.
They'd be distinguished by their hair colour, with red being the most common. Wood lathes are well within the technological capability of Redcaps as I understand then. Redcaps aren't like Goblins or Kobolds: Redcaps have good craftsmanship, but craftsmanship which is centred solely around killing utensils. While they will use wooden arms over their hands, they wouldn't arm their entire army with wooden weapons if they had the choice.
Here's some ideas for Shrubland Gnomes.
1. Shrubland Gnomes don't like to get their hands dirty. They "hire"(booze up) Mountain Gnomes to come by and labour for them. The Worker Gnome lends his muscles to build your fortress. He has innate skill in mining, masonry, building design, engraving, carpentry, furnace operating, wood burning, and farming(field). The Soldier Gnome, a veteran of many wars, can be hired in the same way. He has innate skill in fighting, archery and armour use. The House Gnome comes with great cooking knowledge, passed down by her mother's mother's mother. Mountain Gnome hirelings have a greater penchant for alcohol than wild Mountain Gnomes.
2. There could be a special, rare caste of Shrubland Gnome: the Leprechaun. Leprechauns are crazed, and are born fully grown. Slay the Leprechaun and it will drop a golden item of sorts. Perhaps a golden cup, pot, statue or sword. Woe be to the Gnome who travels with a Leprechaun.
3. Booze can be spiked with gnomeblight for devastating effects, and can be used to get rid of unwanted hirelings or pesky wild Gnomes. Other races will pay you exceedingly well for this Mountain Gnome repellent. Beware however, as gnomeblight booze will obliterate your fortress if you let it.
4. Wizards are one in a million children who are born with a magical spark to them. Wizards are as tall and as big as humans, but are born from Gnomish womb. Wizards have unparalleled magic power, and could be utilized to defend your fortress from invaders. Wizards have but one weakness: they are incredibly frail. They are born old and wrinkled, and grow older and physically weaker day by day. Unlike Leprechauns, wizards are not born fully grown. At any second a wizard could die of old age, be he a mere child or a thousand year old man.
