I have the same issue, and with synaesthesia in general. In fact, my first (false) reaction is to disbelieve it when somebody tells me they have some form of it.

I am aware it's real and many people have synaesthesia but, I would guess, it's so far outside my perception of the world that my brain immediately wants to dismiss it. An interesting and somewhat annoying condition of my own brain.

I've had this experience from time to time. I don't have this "on" all the time. This has been useful for stuff like martial arts.

It's possible to empathize with, if you have sufficient skill in concentration and visualization. You can empathize with anything.

From what I understand, we all have mirror neurons.

https://en.wikipedia.org/wiki/Mirror_neuron

So that's probably contributing to empathy in all of us.