“Intellectus,” I said. “Um. It’s a mode of existence for a very few rare and powerful supernatural beings—angels have it. I’m willing to bet old Mother Winter and Mother Summer have it. For beings with intellectus, all reality exists in one piece, one place, one moment, and they can look at the whole thing. They don’t seek or acquire knowledge. They just know things. They see the entire picture.”
from TC

regarding your last question
So it might be difficult to know who knew ,what and when.


edited for accidental vagueness

I have two theories about this.
1) LC == Chicago proper, so it's possible that something happened in Chicago that affected it.
2) As Harry had put so much juice into it and effort in maintaining it, it has a ghost of it's own. lash, Bob and many others have mentioned that to see things outside of the flow in time he has to die. Now ghost Harry interacts with ghost LC now and this affects LC then.