VioletShadow

I returned the souls to the babies in my completed playthrough, but I kinda regret that choice because it feels like one made full of good intentions with not that positive of an outcome. For my current playthrough I might do Wael or Berath path, instead.

No, your only option is to try to fight your way to the main staircase so you can go back up to lvl 1.

Durance! Second and third would go to Grieving Mother and Kana respectively.

As billy said, have you talked to all the spirits? If you have and still can't obtain the information, consider the fact you might not be able to um actually "talk" to them. Finish tower quest in Heritage Hill

Some trees in Eir Glanfath have souls iirc (War of the Black Trees).

Definitely more godlikes especially moon godlike, my favorite

I guess it's a matter of taste then. I found most BG2 companions to be incredibly annoying but I'd recommend getting to know Durance and Kana at least. Their dialogue and backstories are interesting plus they are useful in combat.