[FULL GAME SPOILERS] Who were the Monsters?

[humanoid]

I don't think every monster is supposed to be a person (that gets mentioned in the game).

Nr1 is most likely the UH roboter you encounter in the very beginning (the one that breaks out of the room after you datamined the other UH roboter) since you can encounter the monster in the very same area moments afterwards in the omnitool room if you don't hesitate to open the seal/door.

Nr2 and Nr4 had next to no backstory as far as I know but there could be some stuff in the _supersecret.rar archive, didn't take a look in there yet.

And as for the other proxies besides Akers, again I don't think that there is any mentioning of it in the game.
Makes me wonder though what made them so special to get turned into proxies instead of ending up like everyone else left in Theta?

Not sure what would've exactly happened though since the WAU accessed it a day before Yoshida did.

I'm guessing WAU somehow manipulated the suit so that the next time Yoshida would use the suit, it would take over control, similar to what happened with the Blackbox update in Omicron.