2. Facebook is not just a private company anymore. It's cool to have success, but that comes with bigger public scrutiny, and possibly a lot more obligations than a normal startup who would have only a few users.
3. Don't think this is minor. Facebook will need to evolve, even in the US. This is a matter of Free Speech and Freedom of Thought.
In what sense? Legally they are, they act like one so I am not sure in practice what makes that distinct.
Perhaps you mean that user expectations makes them not "just a private company." In which case I see no reason why that doesn't also extend to pretty much any other much smaller platform in which users complain about moderation or opaque governance (reddit, twitter, linkedin, tumblr etc...). There are numerous examples of change.org petitions asking for kickstarter or some other platform to change how they do business.
Facebook, Inc. is a publicly traded company. An example of a private company would be Dell Technologies.
"Better", for what I use Facebook for, is equivalent to "has more people that I know". I don't expect much from it, and I get what I expect.