Some responses
1) I doubt it's linked, and the amount must be a coincidence. First, because this knowledge should be all but forgotten by everyone but Venat, and I don't really see what she stands to gain to popularizing this idea. And then, there's others worlds you can visit through the last area / dungeon. Deka pente is literally just greek for 15, and as mentioned by Meteion, she lists them by number.
2) I took this answer as "you literally have godlike power of creation from the point of view of familiars / sundered beings", not that they know what sundered beings are.
You're right that Hermes considers that Ancients make choice for the betterment of the star without thinking of the consequences to the other life forms, which is pretty much consistent with how the three Unsundered Ascians behaved in regard to the rejoinings, etc.
They consider themselves as superiors, and they arguably are since they could create us on a whim with a detailed enough concept. Ie : Hermes managed to create something like Meteion. The issue lies in Hermes (and Venat, since after all she sundered them) thinking that lower lifeforms should still have the chance to live even if not up to their lofty standards.
The point of view is interesting, because we (as in the real world) don't think twice about the thhings we create that we deem inferiors : be it food consumption, creating bacterias, cloning, etc. It's just the same idea on a grander scale
3) Not sure it was linked to Dante's inferno, but the 3 from the dungeons seemed to me like kind of criticizing our society :
- Pollution for the first world, as they pretty much killed themselves by making the environment unsuitable for them, until a plague wiped them out. Rings a bell?
- "Peace" through war and uniformizing people's thoughts, refusing opposite point of views, and blaming it on "breaking unity" ;
- The ram people felt like criticizing trying to make life easier and easier, until the point you just don't do anything and lack any clear goal.