I'm going to combine my camera and panorama head recommendations into
one post.
The most critical part of camera selection (IMHO) is that it have a
manual mode. You want to keep your exposure locked when taking the set
of photos. Having a mirror lock feature is also a nice but not as
critical. Manual exposure will also help in setting the proper
exposure for snow scenes.
Shooting a 360 degree panorama in landscape mode often gives me a
confined feeling. You just don't have a lot of vertical view which is
why most 360 degree panoramas are shot holding the camera in portrait
mode. However, if the subject doesn't have much vertical information,
go ahead and shoot it in landscape mode. Landscape mode may be fine
for mountaintop panoramas as you won't have much vertical component in
the scene.
Since your subject will be quite distant, you may not even need a
panorama head or tripod. Rotating around the nodal point of a lens is
critical when the subject is close such as inside a building but is
less important the more distant the subject. Some time ago someone
posted a panorama of a town taken from a church tower. They took one
photo looking out each side of the tower. The final panorama looked
like you were floating above the town and was stitched perfectly.
A panorama head is still a nice thing to have. But in your case, do
you really want to carry all that equipment to a mountain top? Have
you considered a monopod? I've seen several homemade panoheads that
would be perfect for your situation. One was a simple L bracket
attached to the top of a monopod and angled so that the camera rotates
around the tip of the monopod ad the photographer walks around the
camera. I don't have that link but here are some others that may help:
