The flag is likely quite comically large (as in a hundred or more feet long), decently far away, and is being ‘hung’ by basically small construction cranes, which are holding it such that if there was no wind, it would be hanging vertically.

There is significant wind, so its going with the direction.

Zoom in on the connector point and you can see basically a jerry rigged, oversized winch. Theres a similar winch at the other point on the right side of the image, and the crane is presumably out of frame.

Its perfectly in frame because some photographers are quite good at their jobs.

Trump was allowed to stand up because he could, under his own power, and the shooter had already been declared down at that point.