Materials

There are 2 kinds (at least for now)

• Physical materials govern colisions: rebound, friction, etc.
• Visual (?) materials govern the interaction with light (that's a very correct way of putting it). They call this Materials. I'll discuss.

Material (visual) properties:

• Albedo -  In reality the definition of albedo is the percentage of light it reflects, whiteness - blackness, but here they use it for the color when there is no light (strange...maybe they mean under neutral, white light). Albedo comes from latin albus =  white. We can assign one value to the whole oblect or a map.
• Metalic (map and slider) - the way it reflects light,
• Roughness - more on the way it reflects light, see diffuse and specular to know more, later on.
• And there are more maps which can be stored in the chanels of the rgb+alpha images 

WHat I don't know yet is how the maps are atributed to the geometry!

Lighmaps UV

This expression keeps popping up from time to time, had to investigate.

So lighmapping is a way of baking light effect in objects. It only works for static objects and static lights. As is is baked it is not calculated in realtime. In reality a new texture incorporating the effect of lighning replaces the material's native texture and the light can be eliminated (or at least we don't need to calculate it's effect on that object in real time). Great video here.

Wikipedia page

Light in general in Unity

Lighmaps in Unity (starting point)

Now another question that I didnt understand is this UV mapping, though I think I have an idea that this is similar to the way FLAC2D from Itasca works, with local coordinates.

So this answer is great.

UV are the local coordinates of a flat surface with U and V going from 0 to 1. This video explains well what and how a UV map is built, but it really is the "skin" of the object taken out, cut in strategic places and stretched out and mapped in the coordinates.