It’s long, creating variations requires attention to detail, but is just long, not hard once you understand the basics.

The first thing I do (second actually) is link to another thread explaining the lingo and then explain what variation, parent, children and variation themes are

Just checked the links, they are all working. Which one isn’t working for you?

Sure

No

Yes

It matters. Copying the existing product won’t do what you want to do. If you follow the link, you will see step by step instructions with screenshots on how to create the parent. What info to add and what info not to add.

Creating variations is simple enough, but it takes steps. There’s no shortcut, so either you learn the steps or nothing anybody can do for you.

That’s one way to do it. I recommend it because you already have the existing listing that will become a child. This is not always the case, you can create a parent listing before creating a child listing.

Yes, that’s correct. You need the second color (sibling, second child) and the parent.
The parent however is created with different information than the children. That’s where the link I shared before helps.

That’s the right picture.

Yes

Yes. Create a new listing identical to the existing one, but with a different color (of course, this listing will need its own GTIN, name, etc)

You can do this in any order you want. You could create the parent first or last. What’s important is that once you create the parent, you create the relationship that links it with the children listings. This is all explained in the guide.