1 Yes, actually there is no newer windows player version, 1.8.3 is the current player version.
2 https://xibo.org.uk/manual/en/upgrade.html
from your topic I assume this is manual/custom installation on a web server therefore here the instructions for this case - https://xibo.org.uk/manual/en/upgrade_custom.html
3 Yes, with fully implemented playlists in the next major release - Playlists Blueprint