Russian planes have the edge. They appear to be made of Invulneraballonium and move in ways mysterious to anyone whom is outside of the deepest, darkest bowels of the government.
The Japanese planes have some absolutely wicked agility and turn so darned fast.
They have a lot of planes in the game which have not had their flight model implemented fully or at all so some of them use placeholders, assuming that they're using the closest equivalent until that part of the Dev Team can modify them appropriately.
The gun sight gets everyone. When in a battle, before you launch your plane, you have a figure for your gun sights ranging from something like 100m to 800m. I believe that if you set this figure to say 400m, the black lead indicator will be 100% accurate at 0.40km, being less accurate at 0.20km and 0.60km. Nevertheless, aiming is hard and hitting is even harder. Practice, it'll come.
Important keys
F3 - Standard 3rd person view
F6 - Turret view - If you point in some direction, any gun position that can aim at that point will be under your control. This is a very, very cool system which will automatically give you control of every gunner that can aim where you are aiming and instantly allow any other turrets to be AI controlled. If a gun position cannot point at the direction you are aiming at then that gunner will use the AI automatically. Turret AI is good with enough experienced gunners and can shoot down some planes but manual control is superior. If you need to fly away, dodge and get the hell out of where you are, do not be afraid of letting the AI gunners chew out anything that comes into their range because they can do something positive.
F7 - Bombing View. Ideal for higher level bombing runs with your plane roughly level. If a red dot comes close to dead centre of the heavy white crosshair, press the spacebar to drop a bomb. Press multiple times to drop several. You can move around in this view but it does get tough to aim so try to restrict any movement necessary.
Z - Zoom - Ideal for better aiming at those slightly further away targets, trying to decide which way an enemy plane is moving and ideal for bombing in conjunction with the F7 Bombing View.
Right Mouse Button Zoom in on target. Your camera pans and zooms in towards your currently selected target. Can be useful but difficult to use effectively.
Y Manually reload MG's and Cannons. If you've near exhausted your ammo supply and have the time, press T, get a fresh full load of ammo for your next little sortie. Also clears weapon jams.
Hope some of this helps.