What's the deal with DDC Stage 2? And what about the homes for the new characters?

In Sekibanki's stage, it looks like there's a bridge that spans across Misty Lake. Should we build this once we port over Gensokyo?
And then, as a mermaid, Wakasagihime would probably have an underwater house. Should we build this, too?
And then the japanese title, 'Eastern Castle of Shining Needles' hints at a castle appearing in Gensokyo. How can we make preparations?
I'm pretty sure there will be a castle appearing because of the previous titles in games talking about a building in the game. What do you think?

@Bridge
That would be whatever canal in Human Village is at. The location also clearly states Human Village.

@Residency
I built Wriggle and Mystia's house in Genso and they are ported I think? (Correct me if I'm wrong. Elemeth had a good Wriggle hut as well.)

Wakasagihime needs a sand castle under the lake. She is the Mermaid Princess after all.
Sekibanki lives like a human, so no need to build a separate house for her.
Kagerou... Maybe something like Mokou's hut, except nearer to the entrance?

I still slightly suspect that Kagerou lives in the Human Village, but the chances of her living in the Bamboo Forest are high.
Wakasagihime sand castle: YES

I can help you when I get free time off from game dev stuff. Let me (IGN: pigrid3r) know when I get on :3

I need people to tell me where their builds are because I don't know where ANYONE's wriggle hut is >.>

If you can access players' homes, you can access my creativeflat home to see Wriggle's house, Mystia's house, and a possible 12.3 Nuclear Reactor stage.