Here's what I've got so far.
1) First and most important, is that dragons have a split evolutionary path caused (and induced) by magic. At a certain age (probably 10, maybe more if they're longer-lived than the Ponies) a Dragonet makes their Choice-they either gain wings, move to all fours, and start growing into a full-sized Dragon with a single breath weapon, or choose to become a Kobold, remaining bipedal, but growing taller, more intelligent, and gaining a much more varied choice of flames-everything from Fire Teleportation that works on living things as well as letters, to a jet akin to a welding torch. As Mane lacks proper hands, the draconic society will grandfather her in as a Dragon (ergo the mechanical wings), but Geode has a much harder choice ahead.
2) Dragons are omnivorous. Ponies are herbivorous. How does Mane find out about meat-eating, and how does she deal?
3) At what age does Mane return to Equestria?
4) How different should I make the Draconic society from that of the Ponies? They work metal and mine a lot more, but aside from that, I dunno.
5) Most important, I need opinions-does my work feel like a textdump on the Dragons? I'm trying to avoid that, but I don't really have much else.
This is a serious pipedream, but I'm kinda hoping once the inevitable tie-in novels get started, I can sell it to Hasbro. I've got a Jurassic Park tie-in that was my first book, and while it tends to be very concise (sentences of eight words or less), I think it's a good guide as to what's expected.