What is the ultimate plan for the city in space we're building? Will it actually mean anything? Or is it just kind of a fun way to track progress?

We have some ideas that go further than just a way to track our progress. However, we are not sure yet if we can deliver. So we will say more once we know for sure ;-)

Are there any plans to incorporate HBD and it's 20% interest into the mix somehow? Just wondering...

We have started to collect HBD for several months already on our liotes.burn account. We fill it with a part of the post rewards from @ourpick and we grow it so that later, we can use the interests to burn more LEN tokens.