My first time to Istanbul, need some local info :)

Hi, I fly in later today and am working in the centre for a few days which may turn out to be more frequent visits. Could you please give me some tips on good places to eat and good bars for socialising and meeting professional people.
Also some really cool cultural sites and art galleries if there is an art scene.
Also is the jazz event still on? I am looking for somthing to do tonight as a start to find my way around so can you tell me if there is any jazz on tonight or tomorrow please. Thanks in anticipation for any help and advice :-)