I think you are mixing a few concepts here, which isn't surprising because different game/game engines/softwares/people all have different ways of working...
The only thing that needs to match between your modeling software and the engine is the unit/axis system (1 unit = 1 foot, and where the XYZ axis are pointing). If those don't match, you might end up with objects that are too big or too small, or are mirrored, or rotated to the side, etc. Fortunately for us, in Blender/3DsMax and Plasma, they all match, which make things much easier to work with. All you need to remember is that one unit = one foot, and that the Z axis points up.
Grids are used to help you align and size 3D elements in softwares like Blender/3DsMax. The lines in those grids are displayed each 1 unit, which also help you know what dimensions your object has. However, Plasma itself doesn't have a grid, since it only displays
what you create. Some other games rely on virtual grid in their gameplay (for example, Minecraft, the side-scroller Mario games, and top-down RTS). But that's not the case in Uru, so as Emor said, Plasma doesn't care.
People make a big deal of grids because of one of those two reasons:
- they mistake it for the unit/axis system (which must match between two softwares), or
- they intend to align every object in their environment on this grid.
As you might guess, aligning each object on a virtual grid make modular modeling easier, since all models can snap in like Lego pieces. This makes building big environments much easier, and helps a lot with performances, which is one of the reasons most game engines have a dedicated editor.
However, Cyan always wanted each location to feel unique, which means they never reused assets, which means they almost never relied on snapping anything to the virtual grid. You can still align things in your modeling software if you want, though.
As for factor 2 based textures... All game engines internally resize textures to power of twos (ex: 1024x512, 256x256) because this makes them easier to manage. This has no impact on how you create your environment (unless you're working on a 2D game, which is not our case).