Cool! I knew this was happening, but hadn't had the time to comment. Ok, I'd lke to be god!! LOL, well, Ehecatl is a manifestation of Quetzalcoatl, so...

Oh, instead of using the word cacique, use Tlatoani and the leader is called Huey Tlatoani. That would be the one in Tenochtitlan. Historically, when the tlatoani died, his brother would take the role, he wasn't elected by the people. In case the brother wasn't considered to be well suited for the job, a council would elect the next tlatoani, the Huey Tlatoani accepted or rejected the tlatoque (plural of tlatoani) of other cities.
Next in line are the tetecuhtin (plural for tecuhtli "lord"). This title was given as a reward for warriors and administrators that excelled in their job. They had lands and slaves.
Next are the macehualtin (singular: macehualli) they are commoners, not slaves, that recieved the title of, either, noble-falcon or noble-tiger and did not pay tribute. They could ascend the social ladder by giving very fancy parties and sacrificing slaves to a certain God or Godess.
Those are the "free" groups of society, the rest are artistans, traders, slaves, "the help", entertainers.
Sacrifices didn't happen just beacuse, tenochtlas went to war specifically to get prisioners and sacrifice them, slaves could be sacrificed when someone wanted to ascend the social ladder and when a temple was inagurated.
Well, that out of the way..when do the sacrifices start?
Ehecatl Atzin