I had my first aerial combat several nights ago - got two down before I had to land with engine damage. I was flying the Nieuport at the time, and it was extremely tiresome to have to combat the tendancy for the aircraft to go into a spin, while trying to out-turn the opponent at the same time. A little later I was able to get four down, before again my engine was damaged due to a mid-air, though upon landing my gear must have hit a bump in the field, as the whole thing flipped over on its back. So I became an ace in a night, but didn't live to talk to about it. Beyond always flying in circles, as advised by the experts, I even got the chance to do some 'rolling scissor' maneuvers which ended up working in my favor.
Kilo Delta, it does require an internet connection. Every time you start the game, it automatically checks for updates online, and you must 'log in' before going to do any flying, whether single player or multi-player.