TLS - Keep passport

Hi
my wife has been informed that she needs to send a passport to Berlin TLS (outcome of EUSS application).
she kept the passport during the procedure as a paid service offered by TLS

1) Did anyone use this service or had similar experience? How long did it take to get the passport back?
2) She needs to send a passport to TLS Berlin (from Cyprus). Do they put the visa inside of the passport in Berlin or they send further to UK?
3) Does she need also to include prepaid envelope for return of the passport?

any experience and advice is welcome
thanks