1: The in engine editor I am talking about would mostly be for serialized terrain (saved to the map file) and would be brush / bsp / copy and paste like. Currently I generate a static terrain and lock it by setting it to serialize (it saves and loads from then on out instead of regenerating) and then sculpt over that base. The Terrain generation for non serialized terrain would consist of nodes much like world machine and the like work, with nodes with inputs and outputs that layer over each other to get the correct noise for the terrain required. It could be done in its own graph editor but would be easier and probably more appropriate to just make in BP nodes and send the result to a Uproperty noise variable attached to the terrain to pull the data from. For custom areas of interest Voxel Files with the data in them and the terrain calling a “Custom Generation” delegate event would be the best choice for control from the user I believe.
2: Level streaming with the current setup and serialization should work as expected and as it does with other actors (I will make a note to test this though), the multiplayer chunk streaming I was referencing regards compressing and sending chunk data to clients live so that they can load the world from the server on join.
3: Unreal engine doesn’t support very large actor locations (all actor locations are basic float FVectors instead of something with more capability like a Double), there is work towards supporting it through base world rebasing but as far as I am aware this is an unfinished feature set and is not multiplayer compatible with something where the clients are likely to be in very different locations. As far as the voxel plugin working with it, would have to finish up work on a streaming voxel volume for the server, not the hardest thing ever to do but without multiplayer rebasing working better I am not sure if it is worth the time investment yet.