Oh I had not thought about adding a rotational modifier. That’s actually a pretty neat idea. So I will try it out and let you know.
As for the example, I believe he’s using static mesh components and not actors since we would have to wait till runtime to be able to spawn actors. Regardless, GCS supports spawning of both Instanced Static Mesh component in the editor or Actors at runtime. You can choose which one you want and specify the static mesh used for the former and actor class if its the later.
And yes, the number of entities in a 360 degree circle, number of concentric circles, the radius, etc can be specified directly from the editor as shown below:
Apart from that, if you want to use Actors instead of Instanced Static Meshes, you can find instructions for it here: https://forums.unrealengine.com/unreal-engine/marketplace/1659060-grid-creation-systems?p=1663271#post1663271