I guess you got your answer. Photons are not mass, but they observe mass.
So does this mean that my idea that everything interacts with everything is possibly true?

Neutrinos don't interact with electromagnetic fields, i.e. photons.
Is this hard fact? Or an assumption based on current understanding? Can it be that the interaction is so tiny that it's impossible for us to measure?

They are def. physical things, which store energy and exert forces.
Ok, I mean my understanding of fields is really hazy. I kinda compare EM fields to gravity, which I can sort of get my head around. The gravity itself it not a physical thing, it's a consequence of a phsyical thing. That consequence has energy, because it distorts spacetime and effects mass. But the energy source is mass... I guess my point is that anything that is under the influence of gravity (ie everything) is actually being influenced by mass, something physical, not gravity, which is merely how we observe the influence. Like, when we go down a slide, it's not gravity that is causing us to slide down, it's the mass of the earth. Gravity and mass are essentially one and the same... isn't it the case that EM fields are one and the same with whatever causes the field? They are intricately linked, they are the same physical thing.

I'm sure we've talked about this before, but I have something of a problem with the idea of zero-mass particles. I just think it's very close to zero-mass. I get that even with a mass of 0.000000000000000000000000000000000000000000000000 00001, we still need infinite energy to accelerate to c, so the velocity of a photon hints that it is indeed massless. But I feel that what is actually happening is our understanding breaks down, in particular our understanding of infinity.

If a photon is massless, well it's then going to be my assumption that it is the consequence of something that does have mass.