RTF is a global modification that replaces all towns in the game.

Lizards are boring and depressing.

Don't touch the Lizards!

Mountain Orc race

Brrr... no.

mountain creatures of the earth

Orcs are half-humans, half-demons, but definitely not spirits/creatures of the earth.

1. Goblin Marauder - as suggested, let him throw stones with some kind of effect.

What will the goblin do to an armored crusader with a stone? Better with knives.

2. Orcish Riders - put the same orcs or goblins on wolves with the ability to devour corpses.

Yeah, the wolves will devour corpses, and goblins/orcs will also recover. And mountain wolves 0_o

Mountain Warriors - the basis can be any orcish unit, simply recolored, with two hammers or axes.

...

Earth Lords/Earth Guardians - a mage, only male (we take an assassin instead of an axe, modify a staff with a skull).

Hmm... not a bad option.

6. Borgi - take unupgraded Death Knights from the Necropolis and put them on dark dragons (I saw a model like that somewhere), like riders on wargs from The Lord of the Rings.

Orcs only trust their own kind and despise everyone else.

7. Trolls or Yetis, both live in the mountains.

Cyclops are better, Yetis are the same creatures.

Added after 2 hours 4 minutes
Colors and symbols of the factions (may change)
Church - yellow, sun
Naga - blue, lotus petal
Dark Elves - purple, Arkat
Conflux - green, skull
Necropolis - brown, sword and wings
Lizardfolk - turquoise, two dragons (Silanna and Shalassa)
Orcs - orange, hand (like in G6, G7)
Elementalists - red, triquest