> By the time the FBI comes knocking for your devices, they have a lot of evidence, not a list of hash collisions.

Not necessarily. The FBI knocks on your door when they have convinced a warrant-signing judge, that’s there is probable-cause, or that additional information can be collected to build a case in which the defendant will ‘plead’ or make a deal for sentence reduction. 90% of defendants make a deal and never go to trial because by that time the stakes are so high a guilty verdict includes the harshest possible sentence.

FBI only needs to convince you they can win a case or the judge that there might be fruit behind a locked door, they don’t need direct evidence. It’s really up to the judge.

No, the FBI's job is to investigate whether or not a crime has been committed. They'll do this by getting a warrant for your devices, and then take them and scan them.

I doubt it, all they need is this stuff and they can get a warrant to rummage through your stuff and take all your computers, usb drives, etc and also put your name on a watch list and your permanent record. Much like newspapers retracting mistakes if the story doesn't pan out, it goes on the back page. Plenty enough to wreck your life.