1) In addition, I don't think we have seen people using carts/wagons to move stuff around. This kinda makes sense, because if you want bulk goods from a different level, I don't see how you get a cart up the equivalent of five flights of stairs.
Actually, they did transport Ferrus' collection in a couple of wagons/carts. So they do see some use.
3) It would make sense if one of the staircases was blasted away and an elevator put in place. They do have lift crystals after all.
Are there staircases going between the habbles? I assume that this is the purpose of windlasses, to move people and goods from habble to habble.
6) We also know that there are extensive ducts/vents going between the various levels (for critter and Auroran marine use). Given the tariffs and the traffic, I think it would make sense that there is a lot of smuggling going on through these back routes, and some of the bigger ducts might even be official secondary paths between the habbles.
I am not 100% sure that the air vents go between habbles, or whether each habble has its own separate ventilation. After all, the silkweavers seemed to be confined to Habble Landing.
10) This makes one wonder why more habbles didn't go the route of Landing and make their own holes in the wall. Obviously there are diminishing returns for every extra hole, but think of a habble midway between Landing and Morning. Bringing goods to this habble from the outside requires transport 2500 feet vertically. That means that (e.g.) every beam of wood on this habble required a human to carry it down (probably - up would be crazy) a distance of the tallest building in the world. It would be real expensive.
Spirestone seems to be the most durable thing there is, so I don't think that they could put more holes in the wall even if they wanted to. All of the destroyed masonry we see in the book is specifically NOT spirestone, so they may be restricted in what they are able to/are willing to destroy.