I have a very extroverted 6yo DD, who exhibits some of these behaviours. Very active, endlessly chatty, intensely curious, very clear about what she will and won't do. Like she's got an extra battery inside. There are two local mums with twin boys who watch her in the park and ask me wide-eyed 'how do you do it?'!
I felt I had to put in place very clear discipline very early on with her. And I police it like my life depends on it (cos it does). No doubt it makes me look crazy to others, but it works well on my diva of a kid.
Example:
Mum: tidy up your art supplies please
DD: (dramatic gesture, whiny tone) no! I don't want to (gives 3 argumentative reasons why not)
Mum: (eye contact- steely gaze) think very carefully about what you say next. Art supplies, cleaned up. Now.
DD: I hate my art stuff, and I hate...
Mum: Yes?
DD: Nothing. Fine. I'm doing it (sneering voice/face)
Mum: come back here. Sit down, look at me and apologise.
DD: Sorrreeeeeee (sarcastic)
Mum: (calmly) stay there and practice your tone until it sounds like a proper apology. I'll be back in 15 mins. After that you can pack away your toys in here and fold the laundry in the basket as well. If there's still no proper apology after 15 mins, or I hear 'huffing' there will be no iPad access for 2 days. iPad time is only for grown up kids who do their jobs, and speak respectfully.
And if she does this three times in one afternoon, I go through the whole thing again and again. Sometimes I think I'm just boring her into submission!
To address the fact that she hates to be alone, I make her sit and listen to kid meditation apps with headphones for 15 mins a day. They are very prescriptive about stillness, and are teaching her what it feels like to just 'be' in her own head, not looking for affirmation from outside it. I think when I started she managed only one minute! I encourage anything like this: reading (not out loud), doing puzzles/wordsearch in a far away part of the house, I leave her with 'something to think about and tell me tomorrow' at bedtime.
I am a researcher, so I ended up learning a lot about having (and changing) a person's 'locus of control' from external to internal. Check it out. I guess that the discipline and the mindfulness is actually about helping her develop and trust her 'little voice inside', rather than just express every (positive or negative) thought she has. I see it as just one more skill I can help her with to increase her independence in later life.
Extroverts can be fabulous, fun, energising and useful people. Or they can be grating, contrary, loud and tactless. I'm plumbing for the first version, but it is hard work being so consistently 'on her'.
Good luck to you!