GameModeBase is the parent of GameMode
GameStateBase is the parent of GameState
So using GameMode is the same to use GameModeBase…
You don’t need to put the same logic in all the characters… Make a parent with the logic, and the rest of the characters make them childs.
Look for a tutorial about inheritance and polymorphism in C++. That is exactly what you need.
Then you can watch this series of multiplayer tutorials.
There are many pieces of logic that you could put into actor components.
Personally I think that a good organization of the project and the files is almost more important than knowing how to program.
You really have to be careful with youtube tutorials… Each programmer does what he wants and it is not always the best.
Unreal uses many design patterns. They are the best way to do things. Unreal has already organized everything for you.
You just have to learn to use the tools they have given you.
Best regards!!