The basics

[maddox]

Incan gouvernment did change from the 14th century setup, but only concerning numbers.

The big cheese is the Sapa Inca. The Incan Emperor, always male. In theory he owns the world, except the people. And inside the Incan empire, the emperor "allows" his people to do their things, using his ground, his forests, mountains, lakes, whatever, to live a good life in exchange for taxes. Those taxes can be levied in goods like food or raw materials, but also in labor or manufactored goods.

The taxes/labor are gathered in an originaly decimal- but population did grow rapidly*, and nobody wants too many tax collectors- setup.
Now in the 20th century 100 families have 1 headman, The Chunka kamayuq.

100 Chunka kamayuq report/contribute to the Pachaka kuraka. Meaning that the Chunka kamayuq of an area has the resources of 10 000 families to control/redirect. (+/-30 000 contributing people)

100 Pachaka kuraka report to the upper level of the gouvernment. The Hunu kuraka.

With 15 Hunu kuraka reporting to the emperor, with 3 for each quadrant of the empire, and 3 administer Cusco, Lima and the Imperial court at Machu Picchu, there is 1 chosen to be "president" the first among equals, and the one who has to dare the wrath of the Emperor if there are bad tidings.
In some cases the president was also the Inti high priest, the Willaq Umu, Sapa Inca's younger brother.


Each Pacha Kuraka leading 1 000 000 families (100*100*100), with 5 people per family avarage =5 000 000 people  The 100 Pacha Kuraka report to 15 Hunu Kuraka, would mean there are 5 000 000x15=75 000 000 inhabitants.
This is far from the truth. There ain't 1500 Pacha Kuraka.  Some of the Hunu Kuraka have only a handfull of Kacha Kuraka reporting to them, others do have more and only a few have the full "allotment". There is ample space for growth in this respect.

(OOC, the Hunu Kuraka's can be seen as ministers/secretaris, but legislative, executive, judicial and even religious tasks/post are intermingled. And the Hunu Kuraka get the appointments directly from the Sapa Inca.
Depending on the inclination of the Sapa Inca, this gave way to nepotisme, or even blatant favoritism.
But with the roles of the Lorekeepers and Loreseekers closely woven into the ruling fabric , most Sapa Inca's in the past 200 years have been benevolent rulers and appointed people nominated on basis of more tangible qualities than bloodties or worldly power of the aristocracy. Of course, mistakes were made :), and sometimes even rectified.  )
   

[maddox]

Roles in the Inca society.

Chasqui, the runners/messengers that made the Inca Empire functional when it became big. Making a centralised and coherent gouverment possible. This combined with "Sapa Inca roads" that equaled and even surpassed the ancient Roman roads, the flow of information, goods and armies was fenomenal, even without draft animals.

In the 20th century Chasqui are still important, and becoming one isn't something achivable without dedication and certain physical attributes. But the role as long distance/mountain runner is diminishing. Telegraph, wired or wireless are replacing stamina. Trains are also a reason the running part of the job is becoming less "needed". 
Still,  it's the job of Chasqui to operate and guide the flow of information, whatever means used.
You won't find an official telegraph/lightless Heliograph operator in the Inca empire that isn't a chasqui, not even on the navy ships.
Some argue that the job is hereditary. And there are families that can claim such. Even enobled families. But the ranks are open to anybody possessing the capabilities, and one of the stronger means to increase status. 
In the past, a chasqui losing the physical capabilities due age or accident, had a better chance becoming a Chunka kamayuq. But in most cases, teaching* or weaver were the better options.
Now there are more options , thanks to technology

Loreseekers.  The heralds of Manqu II, a small band of ambitious Chasqui that started gathering stories outside their duties, to please the Sapa Inca, grew in importance. Still, a Loreseeker has to come up trough the old school chasqui training. Only when showing any promise, and mindset, these chasqui will get the further training.
Some will fullfill the original role, messenger and storyteller. Others are explorers, diving deep into the unknown.
And the more ambitious ones, they find their own place in Inti's glory. Is it by returning with important information, or joining Inti in the afterlife.   
20th century "established" Loreseekers can be found as advisors or even leaders of trade missions, expeditions or military endeavors.

Lorekeepers. Originaly priests, keeping the balance and bookkeeping, but with the new Loreseekers, there was a divergence. The priest/bureaucrats kept the jobs, sharing the responsibilties as tax collectors/labor managers.  But others started cataloging the information/stories the loreseekers brought in. And in some cases, working with that information in ways the gods could frown upon.
But again, the influence of Manqu II was strong.  He and his younger brother, Inti's high Priest, didn't like the combination of divine and worldy power in the hands of mortals. Priests should concentrate on the soul of the people, not being distracted by the petty worldly tediousness of taxes and such. That unworthy task was appointed certain members of society (the retired Chasqui for example).
Some of the priests started to gather the information of the loreseekers, and it didn't take long before this became an important task. Learning and teaching from the streams of information.
And one of the tasks was to teach the children of Sapa Inca. Imbuing them with a sense of wonder and glorifying their divine heritage.  And from this point on, the Lorekeepers had their reason of existence , and funding.
Forming a brotherhood of librarians, teachers*, experimenters. Soon the engineers and architects joined that brotherhood (some for the knowledge, others to suckle on the riches from the Sapa Inca favors.)

Manqu II did see an opportunity to make a stable triumvirate to support the Sapa Inca. The nobility/priests as anchient leaders of the people. Lorekeepers as guardians of knowledge and invention. And the military drawing from both to have it's own core.