My nephew is autistic and I am a teacher who teaches some low level autistic kids as well as quite a few with Asperger'sA low to mid functioning Autistic does not operate on your level. There processes are beyond most peoples understanding. He did what he did to deal with whatever "ghosts" he was plagued with. he may not have seen his actions as wrong in his mind (autistic people do not see others as people) this is not mental illness it just the way it is.
The mom thing from what I understand was a rage reaction. he probably had no plan but was simply a prisoner of his emotional state at the time, this is quite common. I think Lizzie gave the best explanation as to the rest of it.