As you may know, autism is characterized by language and social impairment and by restricted/repetitive behavior patterns. You mention some concerns about language, but there do not appear to be social concerns, and the only repetitive behavior that you mentioned is repeating words.
Of course, diagnosis requires a thorough, in-person assessment. I would certainly encourage the family to seek an assessment if they are at all concerned.
I would not be concerned about offering multiple forms of communication (e.g., sign, spanish). The data on infant signing, for example, indicate that signing does not intefere with development of vocal language.
I think the only way to find out for sure is to have him assessed by a speech and language therapist. I think that hearing different languages can sometimes make them later to start talking (but having said that my daughter was bi-lingual from 9 months onwards). My son was only saying 2 word combinations at 2+ years and he began repeating words and phrases he heard people say or from the TV. He went on to get a diagnosis of an autistic spectrum disorder. I am not suggesting that that is definately what it is, but you have your concerns, and if this boy is on the spectrum then the sooner he receives input from professionals the better the outcome.
I would also like to point out that being on the autistic spectrum does not mean a child cannot hug, kiss or show affection. Those on the milder end are able to do this to varying degress (along with show imagination and have some theory of mind), although they may have other social interaction difficulties.