Okay, here's a couple things.
First, if your level is always going to be perfectly spherical (or you always want to treat it as perfectly spherical), then the surface normal is just the player position relative to the sphere's origin.

Secondly, I wouldn't have an "absolute pan", since that just won't work rotating with arbitrary axes. This is explained a little bit in this thread that deals with a very similar problem, which is ultimately resolved using this function.

I hope these are helpful.

Jibb