I have virtual rounds for FB and I have a few questions.

1. Do you always have to solve 2 questions in 40 minutes?

2. How much freedom do you have when solving questions? Do interview tell you which approach to take? eg) DFS vs BFS. I am wondering because some questions are much easier if you pick a certain approach.

3. How to run/test the code? Do I speak out how code runs, by lines? or do I actually write a test case and "press" the run button?

4. How do interviews know whether your code is bug free and not missing hidden edge cases? Are they just really good? or do they actually run your code against their test cases?