You are the mean of the 5 people you spend the most time with. So always try to surround yourself with people you can learn from, especially in the first years of your career.
I personally find that the best growth comes from people that challenge you and make you challenge yourself.
It's what the culture has turned into. You are expected to do a white board test. It is more of a test to filter out those who are passionate enough to study for weeks before an interview than anything else. But it's part of the game.
I agree. Copy and paste is on the left hand for QWERTY. That gets a lot more use compared to select-delete. Besides, select and delete with the mouse is seldom the most optimal (and you could just cut the text with ctrl-x)