Can I combine normal mapping with spheremapping on the iPhone?
is it possible? probably.
can you do it with unity iphone right out of the box? no.
More importantly: would you want to do it: for a still shot or similar perhaps but otherwise the NM - sphere mapped object will more or less be the only thing on screen due to the pretty serious requirements it has. ipod touch 1st generation would definitely not be meeting those requirements.
So what would the shader that combines normal mapping with sphere mapping look like? Could it be done in 1 pass?
No
You can only have 2 textures in a pass. With Diffuse + Spherical + Normal Map you are on 3 and therefor require 2 passes
I don’t think there is such a shader around so you will likely have to consult the shaderlab docs and the present shaders (the default ones for regular unity are all source available on the resource page) to built you such a shader on your own
So would the normal mapping change the addressing into the spheremap, or would it simply change the normal wrt the standard lighting?