Are you a vegetarian? Why? Why not?
No, I'm not a vegetarian, because I think that a well-balanced diet should be have meat, fish and dairy products. I respect the vegetarians's opinion, but I don't share it.
Excellent! Just a couple of minor changes. (the "a" in the first sentence isn't strictly necessary, but it sounds a bit better to me as a US English speaker)
Thank you very much :)