I'm sorry I have no ideas for you about the behaviours. There have been a lot of good and probably more educated or experienced suggestion than I could give.

The only 'behaviour' I will comment on though is your DH's Just because your DS isn't talking doesn't mean he doesn't understand. Even if he doesn't understand the actual meaning of the words he is hearing from him, he will understand the sentiment. It certainly won't help his progress or his self esteem and it definitely won't benefit his relationship with is dad. I'm guessing his dad doesn't know what his comments could be doing, he's just got a bruised ego and that's how he deals, but it's not good for your poor little man or you to have to worry about it

I hope you get some answers so can get on top of whatever is going on with your DS soon (If there is something wrong, but if your mummy instinct is saying there could be then go with it, it's usually right. But I had a friend who didn't say a word until he was 4, then one day he just said "Can I have a Vegemite sandwich please mum." and decided from then on he would speak. )