Hello Look ahead
Re your questions.
In the 9 August 2006 and 6 August 2006 APOD photos, the two Magellanic clouds can be seen along with lots of other stars filling the night sky.
1) In such photos of the sky, are all the stars from our Milky Way?
Many of those stars are from the milky way and many are from distant galaxies.
2) Are stars from other galaxies able to be photographically captured in such panorama of the night sky?
With the telsescopes we have, we can flood the screen from other galaxies. But! the stars witin our milky way will have better contrast because of the shorter distance.
4) In the space between galaxies, is it emptiness or are there stars and gases?
The term empty is difficult to answer. Nothing is empty by definition.
But! if you eliminate the very few photons, neutrinos amd Hydrogen atoms, yep its quite empty.