I believe telling people (who have a need to know or regular contact) when a child has challenges which affect others. My son has ADHD and some processing delays. This can look like he's not even listening sometimes-- he really needs to take a long minute to sort out what he's being asked to do. We also know that transitions can be hard for him when he's hyperfocused, so letting teachers, instructors or parents of friends know that he needs some extra guidance in this has been helpful. (This way they know he's not willfully ignoring them, but can give him extra time to move out of one activity and on to the next.)
Please let your husband know what I have seen: most people*want* to help children who struggle. If we give them concrete advice or information, they are often more understanding than if we try to downplay it. Sharing information--and use wisdom, obviously-- tells other parents that A. we are aware of our child's behavior and its affect on others and B. we are being responsible in helping them to know how to help when they are with our child. Community is so helpful. I've had mostly good feedback from other parents...some aren't going to be understanding, some might even dismiss it out of ignorance, but by and large, most people WANT to help. More people are aware of autism these days and aware that many brilliant people are autistic.
And in answer to your other question, talk to your son about his diagnosis. My son asked me about an advertisement for Concerta or something else, when I told him that "sometimes, some people need a little help focusing and this makes their brains go a bit faster" he said "I wish I could have that!" and thus, we had a great entry in telling him that he did, in fact, have ADHD. We've also had talks about some of his heroes that have ADHD and are successful in life. Who knew that the creator of Captain Underpants would have played such a positive role in how my son sees himself?! So, share information wisely and with the intention of helping your son (don't complain or go on about how hard it is, that won't help). You'd be surprised at how helpful and understanding people can be.