I haven't read the entire thread thoroughly or looked at the map, however I'll answer the questions to the best of my ability:
1. Dropships should only be able to load/unload at the beacons.
Hard to do without side effects. One way is to center a location over the dropship. If there isn't a beacon on the location, then load any units into the transport. The other way is to give the dropship to another player. The third way is to use a virtual dropship system, which would unfortunately limit the number of dropships you can have to a theoretical number of unused but placeable units and storage space on the map.
2. Dropships should only be able to move among beacons (i.e., if they are not over a beacon, they should either be moving to one or they should be prevented from load/unload).
With infinite beacons, I can't see this being possible.
3. More than 1 dropship can be in flight at a time. (not as important, might be 100x harder this way)
Not that hard, but will cause problems if they overlap, unless you use a virtual dropship system, in which case you can mark each dropship with a unit (which can't be unloaded due to script).
4. Theoretically infinite beacons and dropships must be possible.
I don't think you can do infinite dropships easily.
Problem 5: an airplane flying over an airport that is NOT its destination, should not stop there (not really that important, but hey, i've been surprised before).
again unlikely. The problem is you need a target other than the dropship's target.
Problem 6: when a new Dropship is produced from the starport, it should fly to the nearest Airport.
Easy to theorize with virtual dropships. Put the new dropship in a mobile grid, or sequentially larger locations.
In order to freeze an air unit (or ground unit) you can move the unit to a location whose center is off the map. You can edit the location off the map by clicking on location properties in scmdraft, or just dragging it in starforge. Don't touch the location afterwards or it will be "fixed" back to the edge of the map. So long as you don't edit the properties again it will work.
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