^It could play out that way too. Either way, the Cardies former homelands are footing the bill. You could call it "diplomatic plundering."
As for Septimus III, we do have a shortage of information. However, even if the Klingons planned to slaughter the entire Eleventh Order outright, so what? They're Klingons. That's kind of what they are known for. Hell, they probably had their opera boys write several epics about the battle. It's not something they're going to be ashamed about, and it won't be something that can be used against them at the bargaining table.
Indeed. It's something that makes me a bit uncomfortable about the "cult of St. Martok" sometimes seen around these parts. The guy's a sensible, pragmatic Klingon... but he's still very much a Klingon, down to laughing and celebrating in the ruins of Cardassia Prime.