Refractive index of glass for the VIS light is about 1.5, meaning that light will be reflected with some ratio (say 0.04, if we have normal incidence and semi infinite media). It is obvious for many photons, but how does it look for only 1 photon? How will the ratio of the reflected to incident intensity look like? Will it be 0 or 1? Or is there a flaw somewhere in my reasoning? How does the polarization comes into picture here?
Reflection is probabilistic. Meaning that each photon has a probability of 4% of being reflected.
For the purposes of calculation of the unitary evolution of the one-photon electromagnetic field state, the refractive index is exactly the same as for a classical field. As a quantum state, such an EM field propagating in matter is simply a quantum superposition of a one photon free EM field state and excited matter states. The EM field is coupled to the excited states of all the matter atoms / molecules at once in superposition. See my answer here or here for more details on these issues.
As BoyFarrell's Answer says, the actual reflexion, as measured by a light detector, is probabilistic, with each launched photon having a probability of being reflected and detected (assuming the detection aperture is big enough) of a value given by the Fresnel-equation caclculated reflexion to incident intensity ratio.