Yes they can. In fact they should. You can just keep adding variables to the save function right before the Save Game to Slot node. Just remember to duplicate that variable in your savegame bp so that it has something to reference when saving. Ive added this to the amended project.
You’re exactly right. just add the same actor to each level. All it does is track data and its empty except for the code. The reason you do it like this is because the code is not activated UNLESS its a “live” actor in a level. So you make code that sits in the level waiting to be called. If you just make a blue print and all its doing is sitting in your content browser, it is never active in game. This method is important because good code is simple and has simple functions in many different places to be called rather than one giant complicated function in one place. Its easier to organize and reuse code this way.
This is the link to the amended project: