In what application do you want to render? As far I know in several applications the default materials already have a detail textures input, at least I remember seeing inputs in standard Unity material, Mamorset material and there is a detail texture material function in Unreals material editor too.
The offsetting of UVs into grid squares is just a convenient way of organising UVs assigned to different materials. The big UVs are - as you surmise - a means of increasing texel density There is nothing special about UDIMs - it's just a naming convention for a standardised system of managing multiple material assignments…
No, you don't "apply the reflection map to the body" - you start by look up how reflection mapping (of any kind) is done in the Maya realtime viewport, setup some test scenes accordingly to understand how it works, and then apply what you learned to display this model as desired. (of course ultimately the reflection…
Ahh, okay. Cool. :) I'm not sure about the spherical projection. Is there a way of finding out in Maya? As to a second UV set - nope. It looks like there's just the one. I've temporarily moved other UVs out the way and placed the torso/jacket UVs in the first UV slot and then enabled that texture. It's only covering the…
I think.. there are two reflection maps applied to the model based on surface. the smaller one is used on non-shiny, non-metal surfaces because a blurry reflection makes the surface less mirror like, the larger will be used on chrome or whatever cos that'll look more like a mirror I would expect they were using spherical…
The general workflow for creating smaller maps like this would involve either painting them manually or extracting them from other texture bakes. Once you have the smaller map, you would export it at a lower resolution than the base maps and then apply it to the appropriate area of the model. If you're using a painting…