1. Motion of Galaxies: the terms "Redshift" and "Blueshift" describe how light shifts to shorter or longer wavelengths as objects in space (galaxies) move closer to us or further away from us. If an object is moving away the wavelength is increasing (so it's getting stretched out). This is what we are seeing in the Universe and why it's a key evidence to support Big Bang.
3. Abundance of H and He: because of these elements being "lighter" and only made from a few protons and neutrons they should have been the first created minutes after the Big Bang event began.