I don't think that is the case. The kinetic energy of these super-energetic particles is often compared to a tennis ball. But that energy isn't released at once, so even if it would interact with yourself, that interaction creates a particle shower that takes most of the energy with it. I don't think we can feel one of our atoms getting violently ripped apart.
indeed, but note that c^2 is just a factor to convert between units here and is completely arbitrary (or rather, c is so high because our units are human scale)
indeed, in the most natural systems of units in this area, we set c = 1 as to simplify the equations