How do I order my flight of Stukas to dive-bomb?

[Ataros]

You should set a waypoint type to "Attack target" for Stukas. If you set your waypoint to "Normal flight" they do exactly what ordered (fly normally and not attacking anyone)

Then you must select the ships as targets for this waypoint. And iirc set type of attack to divebomb or auto.

If you set the waypoint alt high enough for divebomb they will divebomb (3500 m. to make sure, but may be a lower). If they do not have enough alt for a dive they will level bomb.

In general aircraft follow instructions of the mission maker set in waypoints.

You can ask FMB related question in the FMB section where you have more chances to get answers from mission-makers http://forum.1cpublishing.eu/forumdisplay.php?f=203