I was never able to convince myself that Alex got all that information from "research". Even Laura didn't know the details of Kate's travels which Alex knew. I was certain that he had placed a bug in the coffee maker through which he could listen to all conversations in Paul's office.
shareThe bug in the coffee maker is a great theory; it makes even more sense considering how hard Alex fought to keep the coffee maker in Paul's office. You're right, it is unlikely that he simply "knows people" that could give him personal intel on everybody in Paul's life.
shareHe probably hired a private detective.
Religion is regarded by the common people as true, by the wise as false, and by rulers as useful.