I think parent's point is that "director" is the vanity title for these ICs. IC is a normal label found anywhere in and out of Silicon Valley.
No, it's the other way around. They were saying that some directors (managers of 30+ employees) held an official position of "L9 IC" - since L9 IC is much more respectable than a director, which would be something like L6 on the management track.
Yes, this. The IC title is harder to get, and pays a bit more.