@retroven As recommended have a look at the docs, but here is a couple of quick answers

Most popular emulators are already installed and will show up automatically when you add roms. Optional emulators can be installed from retropie-setup if needed but for that you will need the docs Adding artwork is easiest using a scraper such as skyscraper https://retropie.org.uk/docs/Scraper/#lars-muldjords-skyscraper Not sure but probably. I haven't updated on my pi as it is all set up and working great