Here's what we do - for some ideas.

Argh, the whinging and nagging! It must be the age
I mostly ignore the first 2 - I figure there's no point engaging when he's like that. DH keeps trying to talk to him and just gets mroe and more frustrated
If he's really insistent, I just tell him I don't like the way he's behaving and reiterate my answer 'no'. But also offer him some alternative activity, sometimes that helps. Or I'll suggest that if he does what I want him to do, then we can do x together.

3 - DS doesn't do this much. I generally just make it clear that it's not ok and remove myself. He's more likely to hit himself or the furniture, actually. I make a joke about the 'poor furniture'.

4 - If he's mucking around at dinner, we ask if he's eating or playing. If he's playing he's done. Or we might threaten to eat his food or give to the cat. If he still doesn't want it then he can go. I'd like to keep him at the table, but even DH won't sit there through a whole meal....so I have discipline issues there too
Anyway, I would not make a fight about this. If he doesn't want to eat, then I see no point pushing it.

5 - If it's something important, i get right down and make eye contact. To be fair, I don't pay attention to a lot of his chatter, so maybe it's just poor role modelling on my part
If it's something he is not allowed to be doing, then I intervene - remove him or the object or whatever. They get so caught up in things sometimes I don't think it's always entirely on purpose.
The other thing is that we always give lots of advance warning when changes are coming. We use 5-3-2-1 countdowns and tell him what's coming next. We also give him choices if he refuses. Don't want a bath, ok, then we'll go straight to bed. His typical response: ummmm. Want a bath!

6 - at bedtime, again, we have specific set expectations. Daddy reads 1 book on the armchair, and 1 book in bed. Then lights go out. Then he has some songs & cuddles. Then good night. He still complains - why? when it's always the same..? - but he accepts it anyway. And if he tries to deviate from the plan, then he has an option - either we follow the plan or mummy/daddy leaves the room and he's left alone.
This routine is open to negotiation if, for eg, DS is sick or something and he needs extra cuddles or help to sleep.