Can you start a flight without being on a runway?

Possible if you go to "Location" select an airport from the map and then click the white airplane symbol not on the runway. Then the aircraft will be ready for taxi usually.

You can also start a flight in the air from the Location dialog: use the slider on the right (altitude tape style) to move the aircraft upwards. Or on the map click anywhere but an airport...

And you can also select the approach by, once again, going to "Location" and then selecting the airplane symbol in the approach for the runway.

Yes there is no cold and dark option yet that can be loaded from the menu, since no default aircraft can be set cold and dark yet.