They are definitely a thing, but not all walls need to be load bearing. This is the sort of thing they work out during one of the early stages when they make sure the architect has actually designed something that can be physically built, plenty of (most?) architects even do this themselves as part of initial design work and it’s not something you see as much in the modern era of with computers to help make “sanity check” calculations like this part of the design process, like a pre-commit hook linking your code they can check that they haven’t got major structural elements like load bearing columns or cantilevered spans that can’t be built with concrete and steel. It won’t necessarily ensure the design passes local building codes, but it will definitely help avoid embarrassment for an architect of having to redesign something because it literally could not be built as designed by them.

Not in the school of architecture to which Niemeyer belongs. The internal concrete structure and non-load-bearing walls was key to Le Corbusier's tower blocks. You can see this by the fact that the walls often don't extend to the ground, where the building is supported on open pillars, as in the building in TFA. Modern skyscrapers are just a development of the same principle.