CONF, every bit of footage of a search briefing involving police and volunteers I've ever seen includes a display of examples of what they will be searching for, whether that be a photo or a near-identical object.
The report states that engine behaviour was normal, meaning that the investigators compared the full FDR data to expected behaviour. They flew the aircraft for real to determine why the elevators briefly deflected nose-down. In other words, they acted on the allegations made by Asseline and in the latter case backed up what he said, though that behaviour also turned out to be expected.