Texels vs Units vs Pixels in Lightmaps?

So in the configurations of the Lightmapping I have a lot of strange settings and can't quite understand how they work together:

• First off texels = pixels, right? So texel is just a fancy name for a pixel?
• Lightmap Resolution in texels per unit. What is unit in this context? And how does it fit that stuff in the constant Lightmap Size (let's say 256 texels=pixels)?
• What is the difference between Indirect Resolution and Lightmap Resolution? And why I can't adjust Indirect Resolution in Progressive CPU?

 

Texel -> Texture Pixel, so yeah, sort of.

A meter. (or it's what you decide to be. It's "1" in the transform position of a gameobject in your scene)

I'll reply to this later, but it has to do with enlighten being really slow with high resolutions.

 

Thanks!