Why did you export the stories as .txt files???
You can copy from the opened file to your new document.
There's no need for txt files at all.
That makes sense. I guess I'm just in the habit of having a text file...
Oh, well there was thing I was hoping to accomplish, and that's to have texts that were free of formatting, just in case anything snuch in through my new style sheets.
You could use Break Link to Style before copying, or Paste Without Formatting after.
(Your rectangle-with-X problem is caused by mismatched text encodings; you can check the Import Options button when placing a .txt file to figure out which text encoding you're using. I suspect that there is a similar export-options button when exporting the .txt file to begin with, but it's not something I need to do so I can't recall off the top of my head.)