(1) is perhaps more of a question requiring a strict definition of consciousness in the first place, making it mostly circular. (2) and especially (3) are the most interesting, but they seem part of the easy problem instead. And I’d say we already have indications that the latter option of (4) is true, given your examples from (5) and things like sleep (the most common reason for humans to be unconscious) being in distinct phases with different wake up speed (pun partially intended). And if you assume animals to be conscious, then some sleep with only one hemisphere at a time. Are they equally as conscious during that?
My imaginary timeline of the future has scientific advancements would lead to us noticing what’s different between a person’s brain in their conscious and unconscious states, then somehow generalize it to a more abstract model of cognition decoupled from our biological implementation, and then eventually tackle all your questions from there. But I suspect the person I originally replied to would dismiss them as part of the easy problem instead, i.e. completely useless for tackling the hard problem! As far as I’m concerned, it’s the hard problem that I take issue with, and the one that I claim isn’t real.