First of all you have a profound issue with accepting the idea of "photon the quantized excitation of the electromagnetic field".
Light waves, you're good with that. Spherical, flat, standing light waves and even impulses. Just as Planck liked to think about them. But a light .. like a particle? "Naah I don't buy it!" Am I right?
I had this problem for a very, very long time, and it stems from thinking that distortions/waves in the electromagnetic field (or any other field, say gravitational) should at least resemble waves in water. And Maxwellian spherical light waves do that very well. Photons - unintuitive, dreadfully, in this manner.
Until you see this - http://www.youtube.com/watch?v=mHyTOcfF99o - you've probably never seen kind of waves in water, but they're legitimate, as smoke rings from cigarettes. A vortex ring is a stable, quantized directional wave, strongly localized, with a given energy, velocity, and angular momentum.
Since I'm freshly registered, I can't post pics thumbnails, but this is what I would point my finger to - vortex ring
We all need to observe nature more often.
Just imagine those flying around in the electromagnetic field between two plates of the capacitor (more precisely - distortions in the electric and magnetic field intensities, and thus also distortions in the total local energy density of the electromagnetic field, bouncing between the two plates). Just like with a gas of particles, say air, in case of isotropic pressure (constant field strength), the temperature (energy density) is constant between the plates - this is a thermodynamical line of thinking with electromagnetic analogies in the brackets.
Hope that helps you conceptually to get your head around the idea of the photon. Yep, it's unintuitive. Yep, the truth is within the math and the equations, and not in the interpretations and analogies.. but nevertheless, they are helpful. Sometimes.
Sometimes not :P