You don't need every column which is in the exported CSV. The exported CSV is just adding all the information columns, whether they are filled or not.
That way, you can see what columns you can use in your own CSV, but you don't need to have them all. Just add the ones you want.
You can import categories as well. That is explained in the import documentation with examples.
You're going in the good way with your CSV.
CSV import is not complex per se. It just depends what you want to import. See the examples in the documentation. There are simple examples, with 2 to 4 data columns. But then it gets harder if you want to import a whole catalog of products with categories, variants, options, images, files, etc.