Geography of Ysgard

Firstly, TC, allow me to correct your terminology. They're earthbergs, not berms. Now, to answer your questions:

1) Yes, there is a breathable atmosphere in the 'void' between bergs. Most of the Outer Planes have one form of infinite void or another surrounding what passes for ground, and they are usually breathable. Thus, unless stated otherwise, assume that it is safe to inhale. On a side-note, the thermals and winds are so prevalent in the places between earthbergs that only a skilled flyer (or flying mounter rider) or a Valkyre can get through safely.

2) Norway and Fjordland, of course! What a silly question. As for Ysgard, the earthbergs contain seas and coasts to rival any prime world's. Being of a rather nordic disposition in the first place, Ysgard contains enough glaciers and fjords for all.

3) Well, if you're standing on the fiery side, you should have more than enough light to read by. It brings back all the cherished memories of writhing in agony in the Plane of Fire. From a distance, however, an earthberg's fire is visible but only as bright as the resident deity allows. See, the deities prefer to keep both the night-day and the seasonal cycle as close as possible to those of the Material Plane. Thus, if it's midwinter night, not even a close earthberg will provide more light than a full moon.