Hey there! Here is an example of what Kypiq Buildings may look like is from Concept art. But remember is just concept art so it is subject to change, so take it with a grain of salt.
Kypiq will be able to build there homes on different levels, but the nobility will live in the taller trees and closer to the top.
Other races may try to access them but if they weigh too much they may encounter issues as well as if they are too tall. So yes they will have smaller entrances to their homes, also Kypiqs are known to be wary of outsiders in their forest.
Land management will work just the same as regular, they will get parcels and will own what ever trees are in that parcel.
If you look in the concept art they have pulleys to pull up crates and such. As for building homes I assume scaffolding.
So any trees in a parcel they own is theirs. Just like all other lands you can build in other peoples property its just illegal and the owner of sad tree/parcel could destroy your building.
Hope this helps :)