Do you mean a real text variable? If so, you can just use the code ~v which finds any text variable.

It may be that the Kindle device is overriding the settings. In my opinion, one should never get too attached to how something will look when creating a reflowable epub or Kindle book.

It sounds like you were using the ME version of InDesign before, and now perhaps you’re using the US or English version. The ME (Middle Eastern) version can do right-to-left. You can get those features into the English version with scripts or with a plug-in:
https://creativepro.com/typesetting-hebrew-and-other-languages-in-english-indesign.php

Yes, if you want to sever the link to the Google Doc, you can do that. I believe you choose “Embed” from the Links panel. Check the DocsFlow documentation for details, though.

I wish that Adobe included a big notice that said: “Your plug-ins will definitely stop working when you upgrade, and your scripts might stop working.” That is always the truth.

Here are my thoughts on upgrading: https://creativepro.com/should-adobe-fix-older-versions-of-programs/