QED, as in Quantum Electro Dynamics

I got started down this path because I was wondering how mirrors work. Yes, I know light reflects off of them, but why? Some photons are absorbed by the material, which is why anything gets warm when left out in the sun. Some "bounce off". But do they bounce off? Or are they absorbed and then re-emitted? That was my first question.

So I picked up Richard Feynman's QED and started reading it. I haven't gotten very far. Maybe a little into the second chapter, and somewhere he just mentions, offhand you know, on the way to explaining something else, that the photons bounce off. Hmm. Not very satisfactory.

Then I came up with another question. How big is a photon? Well, it's kind of a nebulous thing, and it's a little hard to measure. Well, sure, but there must be some upper bound, and maybe a lower bound. I mean they do these experiments where they send one photon at a time towards some target. If you were to block the photon's path with a wall, it wouldn't reach the target. If you remove the wall, it will hit the target. How about if you put a hole in the wall? How big would it have to be to never impede the photon? Could you have hole so small that a photon could not go through, and still call it a hole?

My latest question is what happens to the energy when two photons cancel each other out? There is "the famous two slit experiment" where light either reinforces itself, or cancels itself out. How about we set up two laser beams, and manage to superimpose them on each other, and then adjust their positions so that the two light beams are exactly out of phase. They should then cancel each other out. But where does all the energy go?

I may have to go back to school, or least go back to the beginning of the book.