I need to create dependend menus (flexible, might have non and up to three subcategories) driven by an xml sheet (how does it need to look like?).

After the user has choosen what he want there have to be an additional output in a textfield (multiple rows for better reading, if possible editable like here (with "wysiwig" in that textfield).

Example:
Dropdown I (choose country) --> Germany

DropdownII (autogeneraed shows all german cities) --> Hamburg

Textfield (will be filled with soome basic from hamburg, pre formatted and editable

How does that work?