To be fair, she's apparently been around more or less for the entire length of human civilization. She's lived under lots of different economic systems, and from her point of view the Federation was basically founded yesterday. Skepticism makes sense in that context, even if she generally approves. We the audience know that by the time of TNG, DS9, and Lower Decks (I have not watched enough Discovery to know if the far-future Federation is still portrayed this way), the Federation has if anything only gotten more post-capitalist, so I don't know that we're meant to read her skepticism as wise. I mostly took it as her being defensive and a bit flippant.

I saw this pointed out in an episode reaction thread, but I'm pretty sure "Tomorrow and Tomorrow and Tomorrow" marks the first time the Federation has been explicitly, on-screen referred to as "socialist". Fans, of course, have been calling the Federation socialist/communist for a long time. I think it started kind of crystalizing in 90's Trek, particularly on DS9 and with Picard's little speech about not using money in First Contact.

It's kind of a throwaway moment in the episode, but it feels big to actually use the word? I suppose modern audiences are much more comfortable with the word than they would have been in the 90's.

This isn't exactly a canon reference, but the "Noonien-Singh Center" was clearly filmed at the Royal Ontario Museum - both the interior and exterior. It's such a distinct building that it really stood out.

You don't calculate the price of something by totalling up the cost to produce it and then adding a bit for profit - you calculate it based on what people are willing to pay. That doesn't really change if it's digital or physical. Some people might be willing to pay a bit more for a physical copy, but probably not many and you'd turn off more people by having the higher price.