"About the skys.  I am planning a series of images where there is no ground, only sky.  Is there anyway to get rid of the horizon line?"

Not that I know of.  I've had to resort to workarounds like parenting everything to the camera, which is no big deal really.  There is an annoying bug that creates brightness issues if you try to use more than one cloud layer, but you can do a lot with only one cloud layer anyway.

C5Pro is a great renderer for Poser.  Subjective territory, but to me it fits like a glove with Poser.