Setup settings is kept on boot medium. It contains everything that is set in SETUP tab in DSS Web GUI.
Configuration settings are kept on system volume (volume group) and contains everything that is set in CONFIGURATION tab.

LVM restore tool allows you to restore volume group configuration from save files. There are 3 save files kept on boot medium, rotated and generated on reboots and each volume group change.

Currently it is not possible to join clear node to failover without stopping it.
This functionality is added to product road map and hopefully will be implemented soon.