I answered your questions on the Youtube video, but don't mind giving some extra details here :). The template is 100% Blueprints with all nodes well commented. In addition, I have a description (in green) on every single Blueprint that explains what the Blueprint does and its general purpose in the template. I also use drop-down lists on many Blueprints to give you choices on how to customize behaviors.
I created this template to be as easy to use as possible, so anyone can pick it up and use it. With that said, its a complex template with many components so it will take time to understand how everything works together. Also, the more you know Blueprints the easier it will be to modify the template to your needs.
I would recommend you take a look at the Creating a Game tutorial series to get a better idea of how I use the template to create a very simple game :)
Let me know if you have any other questions!