Sway sort of does that. It does not resize live, but uses a transparent overlay to show where the window will be. You can do all of the moving and resizing with the mouse this way.

When choosing a bug, if you start with one that is possible to reproduce, it might help following the instructions to reproduce it while debugging the app and observe what happens. This can be a way to start understanding how it all runs. Bugs without context or hard to reproduce are usually more complicated and you might need a better knowledge of the code to have an idea of where to look.

That is incorrect. Both are pretty barebones from the start and have a big pool of extensions to get the functionality that you need. It might be more involved on the vim/nvim side, but that is more of an accessibility VS personalization thing.

There are even sort of distributions for nvim that bring you all the common functionalities already configured.