You are correct, the Aviatik C.I can handle the N.11 fairly well. I found that if I acted aggressively when they attacked that it confused their attack and gave me a good chance of going on the offensive. Remember, you can also fire forward to some extent and that really messes with their heads.
Yeah, it does! My intrepid pilot had a scrap with two N10s the other day and nearly bagged his second victory. I do get a little upset with my gunner though, when he fixates on the one that's further away. Also, he tends to forget about his second gun!