Since you are changing the questions, I am going to copy them.
Q1. What's the culture like these days?
A1. Afaik (I've been here for only ~1.5 years), its exactly as it was before.
Q2. How does it differ from what's publicized?
A2. Not sure. What exactly is publicized? Do you guys know about the unicorns we get every so often?
Q3. Are they stagnating (or becoming slow-moving) internally?
A3. This is a definitely no. One of the teams I used to be part of, got reorganized since the project they were working on (after I left) didn't produce the results expected. All of this took less than 6 months.
Q4. Is it still possible to have a meaningful impact (contribute in a relevant way to a major project)?
A4. Yes.
Q5. In what ways would working at a startup be "better?"
A5. In NO way. Unless is my own startup.
Q6. Does it feel like a large bloated company, or still like a startup?
A6. The options aren't just "startup" and "large bloated company". There is at least one "large lean company", which is Facebook (at least for now).
Q7. How much politics is now present internally?
A7. As opposed to when?
Q8. What are examples of places that have a better culture, freedom, ability to make an impact, etc?
A8. My startup, that doesn't exist yet :P