If I click "Save and continue" -- should it publish the post?
ETA
Yes it published it. And only afterwards the drop-down list with an option "Drafts for XiXiDu" appeared.
ETA #2
This is a bug, don't punish people with downvotes for publishing their unfinished drafts.
People don't expect their draft to be published when they click "Save and continue" if there is a "Submit" button.
Open Office, Word etc are word processors - they're designed for formatting text, and so pretty much by definition they're going to include formatting markup. If you want to write plain text for elsewhere, use a text editor, like Notepad (if you're on Windows) or Vim, Emacs or Gedit (if you're on an operating system, rather than a virus-support program).