Hello,
To answer you second question first: Luxcore v2.10 also exists as standalone, i.e. luxcoreconsole and luxoreui. These can be found in the "Samples" release:
https://github.com/LuxCoreRender/LuxCor ... es-v2.10.1
However, to answer your first question: luxcoreui is not a CAD or shading software, but rather a rendering tool for complete scenes.
This means you can not directly import a .obj file, but you must also provide a scene file (.scn) and a config file (.cfg) that contain descriptions of materials assigned to objects, rendering settings, etc.
If you are really interested, you can read the SDL (Scene Description Language) documentation:
https://wiki.luxcorerender.org/LuxCore_ ... nual_v2.11
But to quote from there:
[... ]normal end-users should not need to edit cfg/scn files by hand.
Based on your message, I would think the best option is to use Blender + BlendLuxCore. Blender can import .obj files and then you can do the shading with a proper user interface.