Short answers: (1) Yes. (2) depends on you’re definition of “needing changes” and (3) No, Elements uses the native designers for the respective platforms, in Visual Studio, Xcode and Android Studio.
But to clarify my second question, I was thinking if Elements has its own visual components that can be used to create applications for all platforms (like for example Avalonia do).
By the end, like Water uses Visual Studio design, how Visual Studio will handle with Elements components if they are not supposed to stay installed there, but only inside Water?
it does not, currently, no. The goal of Elements really is to provide our programming languages for the platforms, and focus on developers writing against the native APIs on those platforms.
I’m not sure I understand this question? You can open your project in VS to edit the GUI parts, and (optionally) use Water or VS for your regular development (ie writing code, debugging, etc).