HiRise,
"My sound problem is not yet solved."
Sorry, I don't know the answer to this one. What you listed as a system should work. Two questions though, are you running the DX8Beta versions or the 1.07p3 version? If you are running the beta version are any of your gun sounds or ack sounds in stereo? The only way you would have gotten those is with some third party sounds.
"How long is 1 square of the map?"
If you look at the top of the map on the right hand side it shows you how long each square is. Each square is a 25X25 mile square.
"What exactly do the 2 graphs under "Net Status" mean and how can i judge my connection with them "
Lephturn can give you a much better answer to that one.
"What is the "Combat Trim""
Combat trim is a automatic trim mechanism that keeps the airplane in approximately good trim. It keeps you from having to manualy trim the airplane for the different flight modes you would find yourself in.