Worldbuilding

http://www.sfwa.org/2009/08/fantasy-worldbuilding-questions-the-world/
Answering questions:

THE WORLD:
>The laws of nature and physics are the same save for magical creatures existing. The laws of physics are defied by magic, but there is no other way to do so
>"The world is generally earthlike physically, but what resides there is magical and new
>There is some ethnic diversity to each race (human, fairfolk,forlorn), but the strife normally comes between species, not cultural relations.
>They were created; they've existed for thousands of years by now.
How many people are there in this country? How does this compare with world population? What is considered a small town/large town/city in terms of number of people?
>Magic comes from relaying one's inherent mana to the "Sruth Diaganta" (holy river) , a cosmic, interdimensional stream of energy normally reserved for usage gods, but the First Civilization learned how to harness this power using focus and incantations. The mortal world then learned to use it again many years later. The stream is eternal and ever flowing, never running dry, but one's mana can. It ties directly into someone's well being like a tether. One normally doesn't have to worry about mana loss, but using magic for extended periods without proper mana control can lead to dehabilitating exhaustion and with usage further than one's capabilities or handling, one can actually draw themselves into the Sruth Diaganta and lose their life to magic. Everyone in the world uses the same source for magic, be it man, fairfolk, forlorn, god or creature.
>There are nonhuman inhabitants in this world; The Fairfolk, faerie like creatures who live in undisturbed natural areas like the deserts, the forests, the arctic; The Forlorn, demonic looking creatures who live in settlements in places deemed inhabitable; and Humans, who live in settlements in habitable areas of the world.
>The world of humans works essentially as it did in 1300s Ireland, with the inclusion of some technological advancements and a greater focus on the development of weaponry and seafaring.
>There is a great deal of land, but a lot of places are deemed inhabitable(but not for the Forlorn)
>The world has the seasons akin to that of regular old Earth.

Physical and Historical Features:
>The story takes place in forested areas and cold wintry tundras for the most part, while visiting tropical and volcanic lands, and enchanted forests/deserts/icelands/jungles
>Humans live in plains, cleared, flat, easy to manipulate landscapes. Fairfolk live in areas that are very in tune with the "Sruth Diaganta", which are mainly lands that are enchanted or can't be manipulated by human invention easily. Forlorn live in areas humans or fairfolk cannont survive in, usually perpetually rainy, or volcanic in nature.
>Changes in the world.
>

Locations:
The _: The ruins of the _ and the direct entrance to the Sruth Diaganta. Looks similar to the Land of Wrath and Angels, the light is illuminated by the energy lying near it, and everything is in greyscale.