Talking about Blueprints and more...

From what I’ve read, I have understood that Blueprints allow programmers to avoid “line” code, and use a graphic development interface.
At the start, I decided to use C++, but the API documentation is poor and untidy. Is the UE4 source code commented? A lot?
On this community I was told Blueprint are 10 times slower than C++, is this a problem on nowadays PCs?
If I use Blueprint, where do I need C++?
GUI… Do UE4 require Flash professional for a customizable GUI?
Should I use UE4? If the end-user system requirements are too wide, the game will be released only for few gamers.
Is Unreal Engine so Unreal? :slight_smile: