They study distant galaxies because they want to know whats out in other galaxies and how many planets it has
That is impossible to answer because scientist don't know ALL the galaxies.
Moving away from us
The light from distant galaxies is redshifted. The only reasonable explanation for that is that the galaxies are moving away from us.
The visible part of distant galaxies is the collection of stars, gas, and dust within the galaxy. These components emit light that reaches our telescopes, allowing us to observe and study the structure and properties of the galaxies.
The light from distant galaxies shows redshift because the universe is expanding. As the galaxies move away from us, the light they emit gets stretched, causing its wavelength to increase and shift towards the red end of the spectrum. This redshift can help scientists determine the velocity at which galaxies are moving away from us and provide insights into the expansion of the universe.
The apparent redshift is caused by the Doppler Effect; the frequency of waves is increased by an approaching source and decreased by a leaving source. Since the fgrequencies we see from stars are slightly lower than they should be, we know that the stars and other objects are moving away. The Doppler Effect causes changes of light emanating from distant stars and galaxies.
The "redshift" refers to the fact that the light is less energetic than when it was emitted; it shows that the galaxies move away from us. Should a galaxy move towards us - which is possible only for galaxies that are relatively close to us - then there would be a blueshift.
The bending of light due to great masses is called Gravitational MicroLensing.
visible light
If you look at a distant galaxy, the light from the galaxy has travelled for perhaps a hundred million years, a billion years, or up to an age close to the age of the Universe (13 billion years or so), depending on the galaxy's distance. Thus, the light you see shows you how the Universe was billions of years ago.
Yes. Lensing magnifies the image of galaxies behind distant galaxy clusters but also greatly distorts the image.
Telescopes are placed in space to view distant galaxies primarily to avoid atmospheric distortion and light pollution, which can obscure and affect the quality of observations taken from Earth. Space telescopes also provide a clearer and more stable view of the universe, allowing for more accurate and detailed observations of distant galaxies.