Tarvis, some screenshots are in the zip itself, although I could make some more later.
LouisdeFuines: There are 3 zip files on that link, one is for the City stuff, one for the Farm stuff and One for the Alien Base. They are named accordingly.
SolariusScorch: I think your hut does not dissapear because those terrains are already used by another map, take a look at the MIB mod and the CULT mod's way to add maps, they remove e.g. one or two terrains from the original maps and give those to the new ones. Just look at the very header of the rulesets to see how its done. I would want to give you a better explanation but I am sitting in an internet cafe atm and can't access my files.
At the top of the ruleset the MIB/Cult Ufo Urban mods have something like this:
Urban terrain
textures (1,2,4)
whereas it by default is
Urban terrain
textures (1,2,3,4)
The new terrain then has something like this:
New Terrain
textures (3)
My mods work differently, though, they are not texture/terrain based.