Welcome to the forums. Some fast answers.
1: The AI’s sucks at finite resources. They mine themselves dry in no time, and then they just die off. Better to leave the finite resources setup for games against humans.
2: Build storage facilities, they should be available from the start. Managing resources are tricky, but you will get the hang of it after a while. Build as many shipyards as possible to have some outlet from the spare resources.
3: Press Q (after selecting the planet). There a bunch of hotkeys listed in the Empire (The Crown) window. Very useful
