Note that there are many tutorials available, the "Nim Days" is already advanced and for special topics. See [https://nim-lang.org/learn.html](https://nim-lang.org/learn.html). The official Tutorial part 1 and 2 are a good start.
For your first question: Some people coming from Python have not even a basic computer science background, for example they do not even know the basic terms stack vs heap, value vs reference type, purpose of references and pointers and such. These people would have to learn some basics before they can write efficient Nim code. For the transition from Python to Nim there is this wiki page: [https://github.com/nim-lang/Nim/wiki/Nim-for-Python-Programmers](https://github.com/nim-lang/Nim/wiki/Nim-for-Python-Programmers)
