Need help with file structure (bbpress theme into my existing wordpress theme)

Hi all, I am making a wordpress theme and I want to add bbpress files to my theme so that the bbpress style fits with my wordpress theme right out of the box.

I read this page
https://codex.bbpress.org/step-by-step-guide-to-creating-a-custom-bbpress-theme/
However, the instructions are not very clear.
It tells me to copy all files except the stylesheet from the default bbpress theme, and then paste it into my theme’s folder.

However, I’ve taken a look at other themes that have bbpress integrated, and their file structure, has all the files in the “extras” folder inside the root of the theme, and then has a bbpress folder, and a bbpress-functions.php

1.) Can anyone please help me with the file structure? How is the bbpress files supposed to be structured inside my theme’s folder?

2.) And in that tutorial I read, it said not to copy the style.css. Why is this? Must I add the styling for bbpress inside my site’s default stylesheet?

3.) Also, what is the bbpress js files (reply, topic, topic.min) for? And do I need it?

4.) If I add bbpress files to my wordpress theme… will it automatically use those file’s styling when my wordpress theme is activated?

Thanks in advance!