Visual scripting is very much a work in progress. To be frank, the main reason you can't find much in the way of documentation or examples is that not many people are using it. It also needs more development work, but currently there don't seem to be any developers prioritizing it over other features for 3.1. You're far better off using GDScript.
As for your questions, all the things you ask about are technically possible, but will require a lot of work on your end. If you're inexperienced in 3D development, you might want to start with something a bit smaller in scope before you tackle such a large project as a 3D Pokemon-like.