reflection of light and the uncertainty principle I've heard that light reflects the same angle that it falls and so if we know the position of photon (the spot where it hits the surface) and the direction of where it shall go - that's violation of the uncertainty principle, so where is the mistake in reasoning?
 A: It's very simple: you're dealing with an huge number of photons and you just know where the flux of photons is going. You don't know where the single photon is going and which is its momentum.
Also considers that, when the photon affect the surface, it is absorbed by the materials; after it is reemitted.
A: When you observe the reflection of light, you are dealing with a huge number of photons forming a beam with radius $\delta r$. Spot you see has non-zero dimension. So each photon has its own uncertainty in position. In addtion, since photons can vibrate around its propagation direction, they have  uncertainty in momentum (vector quantity). (Remember that you are observing the reflection in macroscopic view, so these uncertainties are nothing for you (very small)).
However, the uncertainty principle is not applied for the case above. This principle says that we cannot measure the position (x) and the momentum (p) of a particle with absolute precision. The more accurately we know one of these values, the less accurately we know the other. So, the uncertainty principle determines how well can we MEASURE canonical variables in the same time. When you attempt to measure position and momentum of photon, interaction happens and, as a result, it leads to larger uncertainty in momentum (large error in momentum measurement) if attempting to get higher accuracy in position measurement, and vice versa. 
So, for two cases above, your argument is not true.  
