Updating from 4.9.0.11 to 4.9.1.0 will keep all the settings, playlists, events etc. Nothing will be lost. And it will be like this in the future, starting with 4.9.0.11 all updates are easy and pain-free. You should install the new version to the same folder where you have your current version installed.
To make things safer (and in case you'd want to downgrade from 4.9.1 to 4.9.0 for some reason) I'd advice you to backup the current configuration (read pety's post above).