1.  At baptism, if two given names were given to the child, the first given name was a spiritual, saint's name, orininally developed from Roman Catholic tradition and continued on by the Protestants in their baptismal naming customs.  The second given name was the secular name, which is the name the person was known by within the family and to the rest of the world.  The spiritual name was usually repeatedly given to all the children of than family of the same sex.  For the boys, John or Johannes was heavily used by German families.  If the child's secular name was really John, if and only if, at baptism he was named only John with no second given name. 

2,  The term "Senior" and "Junior" following a name did not necessarily imply a father and son relationship.  It could have been an uncle and nephew who had the same name and lived near each other.  It could even be two unrelated individuals with the same name but of different ages who lived near each other.

3.  The term cousin was widely used to mean an extended family, not the specific legal definition we understand it to be today.

4.  It was a common practice in some German families to name the first born son after the child's paternal grandfather and the second born son after the maternal grandfather.  Here are two more detailed naming patterns practiced by some families:
 
 

For Boys:
1st son after the father's father
2nd son after the mother's father
3rd son after the father
4th son after the husband's father's father
5th son after the wife's father's father
6th son after the husband's mother's father
7the son after the wife's mother's father

For Girls:
Pattern A -
1st daughter after the wife's mother
2nd daughter after the husband's mother
3rd daughter after the mother
4th daughter after the father's father's mother
5th daughter after the mother;s father's mother
6th daughter after the father's mother's mother
7th daughter after the mother's mother's mother

Pattern B
1st daughter after the father's mother
2nd daughter after the mother's mother
3rd daughter after the mother
4th daughter after the mother's father's mother
5th daughter after the father;s father's mother

Whenever a duplicate name occurred in the series, the next name in the series was used.  If a child died in infancy the name was often reused for the next child of the same gender.