An autistic child can be taught just like a regular kid. It just takes the right approach. So while some things (like vocabulary and social interactions) can be taught, others cannot. 

I don't know what you are talking about. Autistic children are prone to violent outbursts moreso than non-Autistic kids. They also do not share well and have problems interacting with nearly everyone. It is up to parents and specially trained teachers to correct these problems. I should know, my mother works with special needs kids in schools (hands on) and specializes in working with Autism. I've had heavy input from her to make sure I represented autism well in this sort of context. She is high functioning and well adjusted, but she is still autistic and still has her problems.

She doesn't control the bijuu, but the tailed beast does not control her. He still looks out for himself, therefore he looks out for her. To break most Genjutsu, you just need to have an influx of foreign chakra, which a Tailed Beast supplies easily. 

Shino mentions that genjutsu targets a specific part of the brain. Mammals have this part, but insects do not, hence why his insects were not affected by genjutsu.