I can't really go into detail about what UV is and how it's used without derailing the thread here. But imagine your 3d model projected in 2d space so you can texture it. If you open up a character texture from Daz, that weird island shapes you see, are the UVs. For my comment above, I'd need to take those shapes, upres them to whatever resolution I want (say 8k or 16k) and then paint the textures on them. (Or clone from TexturingXYZ provided photoscanned real skin textures.)
It is a lot of googling sadly and following tutorials on YouTube, not a process I can easily explain in a paragraph or two.
As for the lights, you are correct that changing the size and the falloff softens the lighting. But that's not what I'm talking about here. A diffuser is an object that when light passes through it gets diffused in the material, which can be accomplished by a simple plain and specific shader values to simulate the material it's made out of. Besides making the shadows softer, it also has the effect of flattening the image (which a simple size change won't do). And yes, the lights I used are all emmisive meshes, then the light passes through a diffuser. A reflector is a simple either white material with no metallicity and high roughness, or a metallic material with high reflection and low roughness depending on the look you're going for. One will have soft light as a result, the other will be a lot more focused and sharp (or to be more precise, similar to the light you are reflecting with it.)
Lastly, the grids. These are used to focus the lights. But not like lowering the spread, more like..directing the light rays to specific directions/angles. Usually directing it forward without letting it split to the sides..But other effects can be achieved too if you really want to.
As for the plugins, besides the toolbox, also get his lights. Will give you all of the above light modifiers and a couple more too, like a beauty dish or an umbrella. For how to use them and what each does, look for portrait photography tutorials.
