The columns are titled, from left to right:
1. Jahr, Mon. u Tag (Year, month and day) der Geburt (of birth) / der Taufe (of baptism)
2. Namen des Vaters (Name(s) of the father): starting with occupation, surname is underlined
3. Namen der Mutter (Name(s) of the mother): "g" or "geb" indicates maiden name
4. Namen des Kindes (Name(s) of the child): typically multiple given names, and often also information on the death where available
5. Namen der Taufzeugen (Name(s)s of the godparents): typically three godparents, with full name and residence
6. This column is only partially visible, but probably contains remarks, the name of the priest or something similar
As for "unused" given names, girls/women often received one very common name, like Anna or Maria, which might not have been used in everyday life, and one ore more other names, often chosen from family tradition, that were sometimes also used interchangeably.