You are prompted at first boot or by running h3disp utility later on. As root. Most recent builds has this function built into armbian-config.
BTW. Armbian is clean Debian OS with support.
Desktop images come with preinstalled Chromium.
There is no onboard wifi on One. https://www.armbian.com/orange-pi-one/ Scroll down and you will see a lot of compatible and tested adaptors. All you need to do is to order one of them.