Whew! That's a lot of obervations to answer in one post!
You've got a good handle on the way affect governs attention, and on the way we learn to deal with/modulate our affects. The empathic wall is a metaphor for the way we learn to handle the affect of others; nevertheless, all of the affect modulation skills we learn become valuable in our struggle to achieve control over our lives.
All of the autistic people I've seen in my office (mostly the adults who have the more minor form) seem to give off affective signals fairly well; they just seem to use the signals wrong. No matter what they do, they seem never to connect with the other person. I don't think that is related to any failure of autosimulation of affect, although it would be interesting to study that in very young children with the syndrome.
We agree that personal experience is important in coding the biochemical pathways for affect, and that early experience makes individual children succeptible to specific affective experiences. I do think that this is the reason some adults who were raised in an atmosphere of terror or humiliation need chronic medication in adult life. There is a lot about this in the tapes from the 1993 SSTI colloquium, but I don't think I've published anything about this in print.