1) Words spoken by 4d beings would be pronouncable by 3d beings with an analogous mouth structure, because articulations and the way you move parts of your mouth to pronounce things only move along front-back and vertical axes (which are preserved when going from 3D to 4D, or from 4D to 3D). As such, I now have a name for my world: Erydai.
2) Day cycles follow the following pattern found at @ https://www.desmos.com/3d/3p2di8qirn . The map projection used is an equivalent of a cylindrical projection, where the sphere is projected to a duocylinder, whose 3d surface is unwrapped to two cylinders, then "unrolled" to a rectangular prism. A 2d slice of each cylinder resembles a gnomonic projection. However, the "latitude" scale used here may shift the projection to something more analogous to the equirectangular.
3) Rain and coastlines are much more important as water sources than the (still 1d) rivers in 4d, cities would probably still appear on rivers for transportation purposes, but don't expect that to be a universal.
4) cities of the same size as 3d cities in population would be like, a kilometer across or smth. in general, the progression of scales would be a lot faster in 4D.
5) i'm using inverse square gravity, deal with it
6) I am going to focus on a small area roughly between the two equators, by the way, just cuz, projection apps for 3d are limited, but projection apps for 4d are straight up nonexistent.