When you don't use mouse aim, you can also easily pull off every conceivable flight manoeuvre (select realistic or full plane control in the settings). I think you can even do more manoeuvres with mouse aim when you limit instructor interference. There's also some setting about "simplified mouse controls" or something like that buried in the menus, but I can't remember exactly where. (I guess you noticed he game's menus aren't an example of clarity
) After disabling this, you should also have more control over your plane.
On a side note: you will find quickly that mouse aimers have a clear advantage over anyone who uses the mouse joystick (which is is different from mouse aiming), controllers or joysticks
To track the plane you are attacking, you can select it as target (if I recall correctly, middle mouse button or "X" are the default binding) and then simply hold down the tracking key (normally "alt"). That only works in Arcade and Realistic Battles, though. In Simulator Battles, you cannot lock targets.