You've been listening to Christians with a too narrow interpretation of Genesis 1.
"How did God create the universe so quickly?" He didn't. The universe is over 13 billion years old, and he's still working with it. Genesis 1 deals only with the Earth and its environs, not the solar system, much less the universe.
What, you wanted God to teach astrophysics to Moses? No, he is more concerned with our souls that with our education. He speaks to our understanding as well. The moon looks like a light so that's what he called it.
"Also, stars are galaxies with complex motion and planetary systems." No, that isn't right. Some galaxies or clusters LOOK like single points of light (stars) from our perspective.
"It is really odd that God took several days to create Earth but he made the rest of the universe (stars) like it's nothing." Again, Genesis 1 deals only with the preparation of Earth to support life and with the spiritual creation of life. The rest of the universe was already in place, including the sun. The trick to understanding Genesis 1 is that it is told from the point of view of an observer on the Earth's surface. As the atmosphere gradually cleared, first light, then the sun, then the moon, and finally the stars appeared.
Those "days" of creation were not 24-hour days, much less consecutive ones. The Hebrew word "yom" can be translated as days, years, or even unspecified lengths or periods of time. So Genesis 1 should actually say, "The first time," "the second time," etc.
The Earth is demonstrably old. There is no conflict between real religion and real science.