Ok, how do YOU attack convoys?

My first big convoy of my career was reported. I found it perfectly in the middle of the night. It had 2 escorts and some American sub surfaced. Ok my question is this. How do I shoot? I shot at the large merchant ( I messed up my speed calculation because I was excited, I was doing dead stop plotting ) but I had saved. So I send 2 torps to two different boats and haul ass? How many should I shoot at the same time before trying to escape? Should I let it pass over me and shoot it in the ass? I know I can't sink it all sadly, but what is the best way to maximize my damage?

Oh, and who is Bernard? People keep mentioning him.