Dealing with a non-verbal 3 year old

Our 3 year old grandson has been diagnosed as autistic. He has no speech at all, just whoops and chirrups. In the past he has been known to utter words occasionally such as "apple" or "bubbles", but we assume this was mimicry as the words were never used again. All attempts to embed the words in his mind failed. There is little in the literature to help those with completely non-verbal kids. How can we tell him what he should not do? How can we persuade him not to regard anything he can lay his hands on as a potential toy? How can we start to get him potty trained? How can we even get him to sleep at a reasonable hour (i.e. not midnight or later)? All suggestions from anyone with experience of this kind of case would be very welcome.

Jim