@Shook: It is possible that giving the bodyslam a high ATTACK_VELOCITY_MODIFIER (say [ATTACK_VELOCITY_MODIFIER:1000] will help it launch creatures more reliably. (crazy powerful attack, by the by).
I haven't experimented with that tag at all, though, so who knows?
)
is there any way to set specific castes to hold specific positions? like, only the emperor caste can be king, the royal caste can be barons, etc?
No-ish. The tags exist but the computer is very spotty about following them. Right now I believe they only restrict player-appointed positions properly. This is something that will likely improve next time Toady makes a pass through the noble code.
also, how crazily can you modify the creatures through castes?
very crazy.
like, could i essentially make a dragon as a caste of a species of rabbits?
Yes.
would the dragon bunnies appear as "rabbits" on screen, or as their caste name, "dragon bunnies"?
I'm not sure. Arena mode would refer to them as "rabbits" once spawned but as "dragon bunnies" on the unit placement list. Castes of civilized creatures are hard to tell apart. However, you can give them caste-specific tiles and Alttiles, enabling them to be told apart by sight. Except in graphics mode, where graphics are assigned on the creature level, instead of the caste level.