1. Which restaurants are the best ones?
---------- Lenne Snack is the best undiscovered one with their special Lenne burger, but almost all of the restaurants in the downtown area are really great. Avoid McDonalds and Starbucks (you can get that at home) and hit up some bakeries and coffee shops, and almost any Imbiss is a great place for a quick bite.
2. How do I meet Germans?
--------- If you're into sports, there's a giant list of activities that you can do for free. There's also a buddy program, but your best overall bet is just to stay away from other international students and throw yourself out there. Make sure to take German courses and introduce yourself to other students. It's best to take those courses on your own if you feel comfortable doing so because you'll have the best odds at meeting new people.