Special Edition content is strictly bonus stuff. We're working really hard to make the game complete as it stands. After we're done with the normal version, the SE class as it exists right now doesn't even make sense to save run results because it kinda doesn't play the same way twice... Although that's still just a concept, it's not playable yet
Yes, we will probably reset progress when the full comes out. That's not 100% decided yet, I think it depends on how much progression changes before release and how people feel about a reset. While our save system is super-crazy-smart (thanks!) it does still have issues with quest stubs and rebuilding progress in certain cases. We'd like to remove those edge-cases by killing the extra events that are saved, but aren't actually there anymore in the game...
And yes, we'll give everyone that pre-ordered Steam codes. Confirmed that during this trip at GDC
And MORE YES to being able to share kingdoms across devices. We've done a lot of work to make that possible!