I was wondering if there is a way to prepare such txt file, which besides the content of the post it also have other settings.

For example the post has assigned attribute reply or create and certain template, which will be assigned to the post during importing file.

I tried to export post to txt file, but after export there is only post content, so I have no example how it should be prepared.

Hi,

use "Directory posting":
http://poster.themasoftware.com/faq.php?expand=faq407
http://poster.themasoftware.com/faq.php?expand=faq304

Just put the .txt files in needed folders and it will have all templates / topics from that section / group.

You can set in "CONFIG" -> "Directory posting" -> to load the files to posts list and not post them immediately if needed.