Regarding the pre-show talk: If my memory is correct, the demon girl (Kirishima) introduced herself as "The Great Demon Emperor of the Demon World." Whereas Laplace has been referred to as the "Demon God Laplace". I'm an anime-only scrub so I suppose they COULD be the same person, but I think that may be a stretch. Btw, your theories sometimes are *wild*, I'm loving it lol.
After-show talk correction: It was mentioned (via a timeskip) that the mana ball in the sky was up there for months (three I think?) before it exploded, not just a day. So Sauros knew about it for quite some time.
This episode (and the next) are some of the main reasons I think this show has top-tier writing. In my opinion, the author is great at writing believable, emotional scenes. Oh, and trauma. He's definitely good at writing trauma, lol. The animation studio nails these scenes, too.
I agree with Griffin that the sex scene was tastefully done. If you think back to all the "lewd" scenes, they were all appropriately portrayed for the message/vibe the author wanted to get across. Two good examples of this are:
1. The Paul and Zenith sex scene in episode... 2 I think? In this scene, the parents are OBVIOUSLY going at it hard, but we only see Paul from the waist up, and Zenith from the upper chest up. The camera makes it explicit what they were doing without actually showing anything more then it had to, because the intent of the scene was to let the viewer know that Rudy is quite obviously aware what his parents were doing during nights (to set-up that they (especially Paul) have a very active sex-drive), NOT to just show gratuitous sex.
2. The Eris and Rudy bedroom scene in episode 8. Although Rudy doesn't go any further then light petting, those camera shots are mostly focused on what Rudy's hand is doing, and Eris' uncomfortable reactions. This scene makes us uncomfortable because the viewer is SUPPOSED to feel uncomfortable during it. We're supposed to not like what Rudy is doing, and know that Rudy is crossing a line he shouldn't be crossing here.
Now we look at this current Eris and Rudy scene, where they actually go all the way. The viewer doesn't NEED to see any actual (or even implied) nudity past a shot or two of Eris' (lightly) clothed chest because all the viewer needs to know is Rudy is turned on before Eris finally pushes him down and says the Magic Words (nyan~). After that, aside from flashbacks of their life together, we only see them kiss, and lock fingers. That's all the viewer needed to see in this scene to know this wasn't just raw sex, but a very intimate moment between the two. TL;DR: People who see the early "lewd" scenes and just write them off as "oh its just anime being lewd to get viewers horny" are missing so much subtle context.