Galaxy Questions

• Does everything get smashed to bits when two galaxies collide?
• Galaxies look stationary, so why do scientists say that they rotate?
• How does looking at distant galaxies allow us to look back in time?
• Why does everything in our galaxy orbit the supermassive black hole at the center?
• Why don't galaxies have a natural magnetic field like the earth does?
• Will the night sky eventually end up completely black because the universe is expanding?