I would spawn the Actor somewhere else or place it in the level and then set the execution local in the actor. The Game State is more to store the state of your actor in the current game not containing the actual actor. The “Authority Node” control is to make sure your Controller/Pawn is the current server or authority holder.
Regarding the replicated variables you can set them to “RepNotify” that will create a function called OnRep_[VarName] that will fire everytime you change the variable. Very good for debugging.
Information regarding game modes an game state: