I was trying to write a short story about the Tau, and I came across some 'issues' with the background:
1) What do the Air Caste do? I know they are given the roles of pilot and messenger. Is that all? I think if you counted the Earth's entire population of messengers and pilots, you'd end up with a very small number. Unless the Tau Fleet is much bigger than we thought. Which leads me to...
2) Are the populations of the Castes distributed evenly? as in, 1/4 each with a smattering of Ethereals? Given the background of Earth caste as the manual labourers AND scientists, it seems to me that they might make up the bulk of the population.
3) Where would the following occupations come from in the Tau society?
b) Police Officer
c) Shelf Stacker (or other physical labourer in retail sector)
e) Professional Athlete
h) Medic (battlefield)
i) Combat Engineer
l) Interior Decorator
m) Fitness Instructor
n) Public Telephone Cleaner ( )
4) We know that Fire Warriors advance in rank roughly every 4 years of active service. How does one advance in rank in the other Castes? I can see an interesting system for the Water Caste (merchants) defined by their success (which means that a Galaxy Financial Crisis would send some Por'O plummeting back to Por'la)
5) Shas'O is listed as the highest rank of Fire caste. But this is still an active combat role. You don't see Generals in modern armies on the front lines. Are there potentially other ranks above 'O for the higher ups?
6) Are there non-combat Fire caste?
7) Do the Tau have a defined (ie, canon) monetary system?
... and thats all for now.