[Ataros]

Yes, spawnpoints and runways are related to an Airfield object, not a SpawnPlace/Area object.

You can rotate a runway and its yellow signs via numpad keys as other objects.

To place spawnpoints correctly assign a Branch key in Game Controls Settings in Builder section.

Place your SpawnArea object closer to your new airfield object than to the original one to make planes use the new spawnpoints.

If you do not place any spawnpoints on a new airfield the planes are spawn on its external circle if a runway exists on the airfield OR on internal circle if a runway does not exist on the new airfield. Circles radius can be edited in FMB or even further in notepad to match the available area.

It is easier to check out others' missions to see how this is done (e.g. try 2 stillborn's missions).