My own theory is that it has to do with Bella's sister. Maybe Bella understands the special bond and would not demand of MC to break it for her.
No he said that while the manwhore path is possible, you'll hurt people this way and they will not be onboard for a harem. Rather one-night stands. But there will be throuples with ending.
Nice idea, where are you planning to keep the discussion about it? One thing I've been meaning to add to my list is the "documentation" for each LI on their status. Right now you all have only my summary
I might just "spam" the forum one of these days to have links for each LI.
As far as we know, it still is, yes. It was confirmed repeatedly in the past.
Amber and Marla are confirmed LIs. All teachers are said to be lewdable, among others.
There is no dark route anymore, it was scrapped a good while ago.
Nami is a goddess, I agree
While the game does not have a harem path, so you cannot just add everyone you fancy as a girlfriend, there will be a few throuples, including at least one for Nami. Ocean hasn't said how he plans to handle other LIs once you are in a relationship with one, but what he has said implied that you can cheat and have opportunities to quit your relationship, so you would have to shoot down a few opportunities for sure.