Pay structure seems to be that of a small, set salary with bonuses rewarded for each Hollow of note killed. It can be inferred from this that seated officers would have an increasingly large paycheck, with the Captain having the highest of all. Based on these assumptions, the Fourth would have the lowest cumulative pay of all the Divisions, as their members are kept away from fights almost completely, whereas the Eleventh would have one of the higher - if not the highest - pay rates in the Gotei.

This probably acts as an incentive for the masses of unranked Shinigami to take on more missions in the living world, which has a double duty of actually fulfilling their duty as psychopomps (beings that ferry souls from the would of the living to that of the dead). Seated officers might have to take a certain number of missions in the living world in order to maintain their positions?

Very high possibility of yearly physicals to ascertain their fitness for the task of cleansing Hollows - it's a physical job, after all! Mental evaluations also very probable. After all you are cleansing formerly human souls. That can't be easy.

Seated officers lead weekly "classes" in things like hand-to-hand, kidou, kaidou, and zanjutsu, as well as more mundane things like how to fill out a bounty claim form correctly, how to write up a (relatively) unbiased incident report, and how to deal with other bureaucratic constructs.

Nonranked shinigami probably have their own divisional book/cooking/ikebana/calligraphy groups, whereas seated officers are allowed to join the SWA/SMA, Kuchiki-taichou's calligraphy society, or Unohana's ikebana group. Perhaps these organisations are the overarching head of those divisional branches?

Oh, look! More paperwork!