Good morning, everybody!

I would leave it out.

Yep.

I think there should be a comma, since there is a pause after "morning" in speech.

So why bother asking?

Because I am not sure if my suggestion is correct. That's why I used "I think". I employed logic but English doesn't depend on logic.

I don’t see any logic. People don’t say good morning pause everybody, they say good morning everybody with no pause.

Again again again again
Again again again and deeper and down
Get down deeper and down
Down down deeper and down
Down down deeper and down
Get down deeper and down
I have all the ways you see
To keep you guessing, stop your messing with me
You'll be back to find your way
Again again again again
Again-gain-gain-gain deeper and down
Down down deeper and down
Get down
Get down deeper and down
Down down…