Regarding Galaxy's Edge, it's been pretty heavily rumored that Batuu (the theme park planet) has something to do with IX, which would make sense. That grassy plains planet with the horses all decked out in costumes & greenscreen prep from the set pics, perhaps? The theme park's a town/city, sure, but guess that doesn't necessarily mean the movie takes place there alone, could get out into a more rural area of the planet too.
Either way, even if the red-bonding-lines Kylo is something Abrams brought along with him after replacing Trevorrow, I don't see why that'd be an issue. Late 2017 to now is plenty of time for them to adjust the theme park stuff, if they needed to adjust the Kylo stuff.
Seems like Galaxy's Edge has given us our first official look at IX too, that Resistance fleet popping out of hypserspace out that FO destroyer window apparently features new ships and stuff. Been a while since I've seen it though, details escape me.
As for a "demonic KoR", can't really see them going that way personally, but guess anything's a possibility. Given a lot of the MSW rumors were proven true with that leaked concept art (Resistance/Rebel troops with "wok" helmets, red-bonded Kylo repaired helmet, Lando in yellow and a cape, young Mon Cal etc), it definitely seems likely we're getting characterization & removed helmets for at least a couple of them though. Whether that's Smith & Russell, who knows. Would make sense though, casting names for those. Man, if Keri's actually a KoR though, it'd seem a little odd having her loyal/subservient to a young guy like Ben all this time though, if they're indeed force users. I almost prefer them not to be, but sounds like they will be of some kind. They all seem to have male builds in TFA too, but guess since we only see them for a split second it's a pretty easy overlook, no biggie.