1) Is artistic development noticably different in autistic children?
"Normal" development of the ability to draw follows the same path almost exactly in people of all ages from all cultural and racial groups across the planet, begining with the scribble stage and moving on through a series of symbol stages that hardly ever vary. As far as I'm aware, no research has ever been done to determine whether or not this rigid pattern of development is different in autistic children or a significant portion of autistic children (i.e., in non-verbal children, or in children who later show savant abilities in drawing, ect.)
2) I'm not sure how this would be accomplished exactly, but a study (or series of studies) showing how auistics process language vs. how Nts process language, what parts of speech are most difficult for them (is there one form of grammar that's easier? Is it the very sound of the letters themselves that are hard to proccess?), in so that we could learn how best to structure a learnable language (a more effective Autlang).
3) This ties into the above. Is language easier for autistics to understand when it's sung? Can instructions be remembered better and performed more acurately when they are sung to the individual? Do we learn better when our lessons are sung to us?