By that I suppose you mean exporting tiles or dungeons to some sort of text file that can be shared? If there was a way to save something to a file (like savegames) while being in the editor, that would be an option. But unfortunately this is 100% blueprint and therefore not possible.
There is no limit hardcoded, there’s just the integer slider that goes up to 4000. If you want more, enter a higher number.
I’m afraid that’s impossible with this system, as there seems no way to spawn an object via construction script or blutility, unless I missed something again.