Sacred Haven of Debauchery

Did I understand everything correctly?

No.
The rules are actually quite straightforward; I can explain them later on Skype.

At what point is the game considered finished?

That's the most difficult question... Usually, we stop when everyone gets bored or the GM can't continue for some reason. Although, once in Dal Shabet, everyone simply died, and those who didn't die were enslaved, so there was no point in continuing.
Ideally, the GM has a storyline in mind, and when it's realized, the game ends, and a finale is written. It's not a given that the players will have achieved their goals by that point, but after that, it's just their individual stories, and the global one is over. That's how I see it.