DRD Team

I'm interested to know if there's a script or line action that can be used to toggle whether a 3D floor exists in the map or not. The example I'm thinking of is a System Shock style force-bridge that turns on and off when hitting a switch.

Yes, just change the heights of the 3D floor until it's beneith the floor with an instant floor/ceiling height script.

Am I correct in assuming that it'd work the same way if the 3D floor were placed above the ceiling? I imagine that having it come out of the floor would cause some problems if a monster were below where it was supposed to go.

If you use a Floor/Ceiling_MoveInstant it shouldn't matter. But putting it above the ceiling might be safer. Moving a platform down is less likely to cause problems than moving it up.
However, the code checking thing positions after the sector movement only acts if the move has altered the nearest floor below the thing and if your move goes above the thing nothing will happen.