I've not tried audio books, but it's interesting if the narrator is doing character voices, why they don't prune some of the 'said's. It would seem odd to add in the monotone he said, after an obvious voice.
This sort of circles back to #18 and making sure the scene is working and doing what it needs to. In which case tagging quite possibly can be minimal.
I think she smiled/he grinned are easy action alternatives when you're trying to avoid too many she said/he said. My first drafts are certainly littered with them. But too many are going to stick out and make the writing feel like a beginners. Try coming up with an alternative action that fits with what is happening within the scene. A kid might bounce when they're excited, an adult might rub at the condensation on their wine glass when they're feeling down. Lots of possibilities. But don't tie yourself in knots trying to avoid them, or that might show through too.
There's an awful lot crammed into #18, Glyn. As you say, it doesn't have to be melodrama. I suppose the idea of the goal is to make sure the chapter has a narrative drive and the characters aren't just sitting around having a chat. Perhaps added to this section should be 'what is seeded for the next scene', to avoid the predictable rhythm you mention.
I came across this link on another writers' site, and found it a helpful reminder of what to look out for as I dive into another round of edits. Hope others find it interesting too - 32 writing rules by Alan Guthrie. I particularly like number 20!