There isn't wind, the pole is segmented with a horizontal bar at the top to stop the flag from just flopping down against the upright. When they twist the parts together on assembly, it causes the flag to 'flap' from side to side a little but it is caused by the movement of the pole, not wind.
You don't see stars because the brightness of the sun's reflected light from the moon's surface and the astronaut's suits requires a very fast shutter to stop it from bleaching out. The comparatively weaker starlight isn't enough to register on the photographic film.