So my wife and child are both Swiss Citizens. I am starting the process for facilitated naturalization. A few problems. I started from a place of having zero knowledge of any of the languages. Also I really really bad at languages (in school math was more my subject).

I am planning to learn German. My questions are

1) I heard some people say that in the interview the interviewer talked in German and you could respond in English to some questions. Is that a common thing? Or does it depend on the interviewer?

2) What happens if you fail the interview? Can you take it again? Or does that mean you will never become a citizen?

3) When we move to Switzerland if I don't have citizenship can I get a residency permit? Is there a time period associated with it? Also is there a restriction on starting a business as a non-citizen.