Apparently someone close to Mark Meadows, was the one who warned Cassidy. i have no
idea as to your other questions. Hope you searched them before asking, as much as i just did.
"I'm not really sure, but was it already public knowledge Cassidy was going to testify?
I don't recall the timelines of news. If it wasn't, how did the 'person' find out? Who revealed?"
It was Plato who said, “He, O men, is the wisest, who like Socrates, knows that his wisdom is in truth worth nothing”