lynx__

No. The 1500m (which is run frequently) and mile world records were held by the same person prior to this, and while the Mile record was considered slightly "worse", maybe one or two people since it was set(Bernard Lagat, Asbel Kiprop) could have beaten it if they focused more on running it, but not really a guarantee.

Jakob Ingebretsen was the other who likely could have beaten it, but he's also been hit by a fair number of Achilles issues, including undergoing surgery this past year.

Kerr's performance was very impressive, and, as he continually reiterates, the team he assembled is what led to it aside from his potential and dedication. He set a PR of 2.68 seconds (two years ago) and before that his closest time was 6.61 seconds away. Granted the mile isn't run frequently, but his 1500m times last year weren't very indicative of hitting the WR either - but also goes to show middle distance and up is often run to win as opposed to set your fastest time similar to shorter distances.

No, there is no official record with and without pacers. And arguably, that's why the Olympics is a bit rarer for middle- and long-distance world records (because you aren't allowed official pacers). You could probably track it down though.

Was the study you saw about carbon plates even for marathon distances?

The directors and organizers of the race control what the lights do. Typically they work with a specific athlete or group of athletes to hit a World Record, National Record, or Meet Record pace.

They are almost always even splits, with a consistent pace through the entire race, though this can be adjusted if the runners request it; that is rare though.

They typically have green lights, which is the target pace, and then a set of blue lights ahead of them, which gives a visual indicator of how far ahead a runner is from the green lights.