I would be grateful if one may kindly answer my questions regarding German Citizenship.

My details;

I have received a letter from Landratsamt stating that I should appear for a personal meeting on "Bekenntnis zur freiheitlichen und demokratischen Grundordnung". They also asked me to bring my passport.

My Questions:

1- What happens during such a meeting? Do I need to take the oath or sign some documents?
2- Will they keep my passport?
3- Whether I will get Einburgerungserkunde on the same day?
4- Does it cost some money?

Above things are not mentioned in the letter. I would be grateful if someone with similar experience may answer above questions.

Thanks and regards.