Don't mean to try to take over 🤣 but I can answer the empathy question on my own behalf. Yes, I believe I experience empathy in a slightly atypical way, but I don't think that it's necessarily intrinsically bad, or that it leads to me harming others any more than anyone else.
You mentioned the part where OP said "as a child I pretended to be upset about a boy breaking his arm because everyone else was" — I'm not convinced that, actually, most neurotypical children or adults would be actually upset about a child's broken arm, unless as you say they were very close to him or there was permanent damage, or if they were actually present at the moment of the injury.
I think, from what I have managed to work out from talking to people and reading, it's perhaps more that they take on and understand very easily the social expectation to react in particular ways, and more instinctively respond with sympathy and sad faces when someone walks in with a new cast, whereas for an autistic person it might have to be more explicitly learnt that you may be disapproved of if you don't do that.
One of my experiences of this was the first schoolday after the death of Princess Diana. I walked into the classroom for registration and everyone was acting weird. It emerged this was to do with Diana's death, and I asked something like, "But why are you upset? You didn't know her, and lots of other people died that day".
And now, in later years, many people discuss it like that, and make out that's how they reacted. But in the immediate aftermath, the general neurotypical reaction, especially somewhere conformist like a school classroom, was to behave like others and act out a feeling of, not surprise or shock, or recognition of a historical moment, but a low-key facsimile of personal bereavement. I probably had feelings not so dissimilar to many others', at least going by how many talk about it now, but hadn't understood the social expectation to act out personal sadness. (I'm sure some were genuinely personally saddened, especially if the death resonated with something in their own lives, but going by how people have talked about it in later years, most won't have been.)
Another area where I differ with mainstream empathetic functioning is that I cannot get any enjoyment out of watching public embarrassment or humiliation of other people, whether I like them or not. I know it's not every neurotypical person who enjoys this, but a significant proportion must enjoy watching things like talent shows where misguided people are encouraged to perform so people can laugh at how bad they are, or You've Been Framed style clip shows where the biggest laughs go to videos that are humiliating and even physically painful for the people in them.
I suppose my empathy is quite unsophisticated in this aspect, because I see a person in [emotional] pain or unknowingly exposing themselves to future [emotional] pain, and it hurts. The contextual and social cues — the type of television programme, any soundtrack, the host's tone of voice, the audience reaction — which presumably act to modify the neurotypical empathic response to one of laughter rather than upset, don't work very well on me.