No, you are not allowed to take any FMs other than those the coordinator told you that you were required to take. This would be unfair to other students - if you already have a background in linguistics and don't need to take the linguistics FM, you'd be getting easy credits and not gaining any knowlege.
Every exam except the master's thesis can be re-taken twice (BAMA-O §13.2), which means you have a maximum of three attempts. Exams taken during the first semester of the program are treated as though they were never taken (§13.1), so they don't count towards this total (they'll show up as "failed" in PULS, but they're otherwise treated like you never took the exam).
For more information, you can check out the Cognitive Systems study regulations and the general Bachelor-Master regulations ("BAMA-O"), although the latter is unfortunately only available in German.
Nearest airport to the University is Berlin Brandenburg Airport. From Berlin Brandenburg Airport, you can take a train connection RB22 towards Golm train station and Golm campus is just 6 minutes walk from there. You can download public tranport apps like VBB or DB to find your way around Berlin and Potsdam. These apps are usually more updated than Google Maps.
Your first priority should be to find an accommodation in Studentenwerk Potsdam. Remember to apply atleast a semester earlier to get a place i.e by April for Winter semester and by October for Summer Semester. Each application is valid for one semester only. List of some other options to find accommodation can be found here .
You should register at Citizen Services Office everytime you change your living address. If you live in Potsdam then you can make an appointment at Citizen Services Office Potsdam and for Berlin you can make an appointment at Citizen Services Offices Berlin. More information can be found here.
As non-EU international student, you only get VISA for initial 3 or 6 months. You should apply for VISA extension or residence permit 6 weeks before the expiry of your VISA. You can find more information here.
Here are some links where you can find job offers:
You can use some job application tips provided here .
Yes, university offers free German language courses for students. You can find more information here.
