Best thing you can do to learn the workflow and figure out how the pieces get together is to watch video series (or even a text tutorial if you prefer) about the creation of an entire simple game. Later on you’ll know how to use these “isolate parts” because you’ll be understanding the whole.
Have you watched Unreal’s oficial tutorials? Here goes some:
3rd person game: BP 3rd Person Game: Introduction | 01 | v4.8 Tutorial Series | Unreal Engine - YouTube
Twin-Stick Shooter game: - YouTube
In these two series you’ll see maaaany subjects and how they get together. Take your time, study them at your pace.
Regarding some of your questions:
- The most common error I’ve seen in beginners is by FAR misunderstanding the scope of a game and trying to make a big game instead of a small one. BEGIN WITH SMALL GAMES, I cannot stress that enough.
4)If you’re new to programming and to game development, I’d say start with Blueprints and bother with C++ later on. C++ is more perfomant, as @Zireael07 said, but you generally won’t need that if your doing small games or just studying. - Build up as you go. Maybe you are too much concerned with details/advanced stuff when you should concern more with simple game development, because, as you stated, you are a beginner. So learn how to make games first, and then bother with advanced/specific stuff.
Good luck! And welcome to Unreal community =)