4. No-one has really solved "flying east"... I mean following the sun (aka flying west), you "gain" time as in you can land local time (@arrival) "before" you left local time (@departure). Going east is a totally different story so you might as well take the red-eye flight and catch a good night of sleep.

So the whole "business" argument of having a full work day flying east doesn't really work. Unless you can fly really really really fast which none of these planes do.

The only gain flying east is less flying time.