5) I suspect Psycho Ami is the only true Ami, and the sweet "real" Ami is just a mask she's otherwise very good at wearing. She is a cuckoo after all. Her primary purpose is to push all the other chicks out of the nest before they hatch so that she can siphon all the love and affection from Akira for her own ends, whatever those might be.
Yeah I'm with you 100% on this. I don't really see any strong evidence suggesting that Ami hasn't been a total psycho the entire time and I see a ton of evidence that she's completely fucked in the head going all the way back to the earliest parts of the game. At this point the only thing really supporting the idea that there's a "real" Ami who's a sweet good person and would never hurt anyone is Maya saying so, and as I've mentioned before I think she's just being ignorant of the truth, whether willingly or because she's been "programmed" to do so.
This might be a bit of a niche reference, but for anyone who's watched SSSS.Gridman, think about the situation with Rika and how she believed wholeheartedly that Akane was a good person, even after it became clear that she was the one behind all the stuff that was happening. Granted, in that situation Akane ends up redeemed in the end, but we're explicitly told that Rika thinks positively of Akane because it's the way she was made and she has no say in the matter. I suspect a similar situation here with Maya and Ami.