Yes, they are notified. It is still your responsibility to assemble your documents on time and notice & complete the missing documents. 

Yes, please plan accordingly and be ready to send your documents via postal mail within the two weeks specified in your admission letter. Also consider using an express mail provider to make sure your documents reach to Admissions Office in a timely manner.

In extreme cases, yes, it is possible. Applicants must explicitly ask for an extension of the deadline before the deadline <zulassung@fu-berlin.de>

Yes, it is sometimes possible. Please inform <zulassung@fu-berlin.de> in this matter.

 A few days after the personal interviews, higher-ranking candidates (according to the Study Examination Regulation criteria) receive the first round of admission letters from the FU Berlin Admissions Office. Then, there is a narrow window of two weeks, in which candidates have to assemble their documents and send them via postal mail to FU Berlin Admissions Office. Not having received an admission letter is not necessarily A final rejection. It is possible that not all candidates accept the offer to enroll and consequently a second round of acceptance letters would be sent to fill the spots in the program