1.a) You can assign categories to fields so they only show for items of those specific categories.
1.b) You can assign fields to the category itself (just change the context to category)
2. There is a field called "editor" which will show an editor. The textarea shows a textarea. Quite straight forward I think ?

Closing as expected behavior.

2 - thank you, I did not understand this right away, because I have problems with English. )))

1 - I mean not linking additional fields of materials according to the conditions of their belonging to certain categories, but attaching additional fields directly to categories.

At the moment, I use the content designer fieldsattach http://www.fieldsattach.com/index.php - it has additional fields for materials and for categories - this allows you to make listing of category materials much more flexible.

Sorry, I figured it out. Looked at the component code))