In principle, yes. Jobs for students are offered at irregular intervals in the Moodle course for the Master’s in Statistics and on stat.de. Special rules may apply for foreign students. Details, further information and links can be found at HU International or at the student staff council (both in German).
Yes, if you are an international student and have to apply via uni-assist.de, you can find the fees on the website under handling fees.
No, there is no specific scholarship program for the Master program. Although you could apply for general scholarship programs.
There are no tuition fees, but some administrative fee (ca 300 €) must be paid every semester which includes payment for a public transport pass for Berlin for 6 months. The exact fees are listed under payment of standard fees and dues on the HU Guide for international students.