OP is the problem ultimately that you feel disrespected by your DH, given that he doesn't immediately step in when he hears his DS disrespecting you? Because that's how I'd feel in your shoes.
So I'd leave it to DH to deal with them when they're fighting, you just try to zone out any arguments. But he does need to keep dealing with them - in other words he needs to parent them, consistently.
Teenage siblings do very often fight like cats and dogs, they will hopefully grow out of that.
As for his DD, at 17 she's nearly an adult, soon she will just want to be with her friends, so I wouldn't stress too much about her.
The problem really is your DH isn't it? He hasn't stepped up and I think you feel disappointed at that. I'd give him an ultimatum - he starts parenting his kids, challenges bad manners every time, thinks of things to occupy them, as how things are right now isn't working.
That's of course if you actually want to stay married to him? I can imagine you're weary of all the drama and thinking of how nice it'd be to have your house back and some peace and quiet! TBH I wouldn't blame you.