coordinate and normal of a pixel

Here’s my two questions about coordinate and normal of a pixel:
1.How to get the x,y,z coordinate of a pixel or a corner of it in the model view?
2.Does OpenGL provide function to get the normal vector of a pixel, which can be seen as a patch of a plane?
If it doesn’t, how to do so?
Thanks for answer me in advance.

normal of a pixel!? Or of the poly rendered at that pixel?