No on all counts.
There was an episode where Picard became disembodied and they had to re-integrate him via transporter. My memory recalls there was a nebula full of personalities in the episode as well. But hell if I can remember which season/episode it was now.
I remember that one, and I found it in the Season 1 episodes - it was called "Lonely Among Us". The episode featured an entity they picked up in nebula, that transferred itself between different crew members and the computer, eventually ending up in Picard, who ordered the ship back to the nebula and beamed over with it. Troi detected his consciousness, and they were able to beam him back.
https://en.wikipedia.org/wiki/Lonely_Among_UsMaybe I've just grown cynical in my old age but the ending to this last SNW episode bordered right on the edge of horrific for me. The nebula brain had already demonstrated that it could create living matter with all the plants and (perhaps) La'an's dog - how does M'Benga know that the grown up version of his daughter is actually his daughter? What if she was just a construct to convince M'Benga that everything is ok now, you can move along, when the actual truth is nebula brain just ate his daughter?
I took it that the Boltzman Brain could either rewrite reality within the boundaries of the nebula to sufficient degree to create the trappings of the book or, perhaps more likely, could create holographic-style effects. I don't recall whether La'an's dog was able to be scanned by the medical tricorder, which could help tip the evidence as to which it could do one way or another.
Looking at it from the perspective of the episode writers, the scene with an adult Rukiya returning was to give M'Benga some sense of closure, that while his choice may have not been what
he wanted, he at least gave his daughter more of a life than she otherwise would have had. That she refers to the entity separately (as "Debra") was meant to show that they're two separate beings, even if they share a physical "substrate", so to speak.
I think of this episode's ending as being in the same tradition as, say, Decker and Ilyria in ST:TMP, or Cochrane and the Companion in TOS, or even Sisko joining the Prophets.