Nope, you're dead wrong on all points. Flight is far more efficient than a ballistic trajectory. Being in an atmosphere is actually really great because wings allow you to lift far more weight than your engines themselves are capable of. And there's no way to 'glide' in space.
Maybe you lack some understanding here. Take the international space station. It is using almost no fuel as it moves along at Mach 22. If you lower it into the atmosphere, and add wings to it, you will use a lot more fuel to keep it flying.