There's a few other things AMP does, it prevents a lot of repaints by allowing the browser to determine the layout of the page at initial load time. All content areas are predefined, so you won't have things change or your scroll position modified because some advertisement loaded 5 seconds in and suddenly you're scrolled up from where you were.
2 is also a bit of an oversimplification. It'll load images if they're likely to be scrolled to, which I expect is some heuristic based on distance below the fold, and it may cause above the fold content to load faster since it doesn't need to compete with below the fold content (on very fast connections this may not matter, on slower connections it probably does).
2 is also a bit of an oversimplification. It'll load images if they're likely to be scrolled to, which I expect is some heuristic based on distance below the fold, and it may cause above the fold content to load faster since it doesn't need to compete with below the fold content (on very fast connections this may not matter, on slower connections it probably does).