RED is a totally separate tool/project outside the scope of RobotFramework. Totally different team out of Poland, I believe.
Having said that, updating to a newer version of the RED IDE is NOT mandatory and although there have been some bugs, the team is usually pretty fast in resolving things. They are certainly very responsive. You can always roll back to a previous version of RED. Again, RED is independent of RF. Theoretically you could write your tests using Notepad or Notepad++ or even Emacs if you so prefer.
Upgrading RF is also your choice and although it is advisable, it is not a must. It is up to you. The RF team is sensitive to NOT introducing too many breaking changes, if any at all. Again, you can always roll back to a previous version of RF if you so choose should there be breakages introduced.
As for Python, yep…same thing. Up to you; not a must. If you are barely starting out I would recommend starting with at least version 3.6 of Python. Even the very latest if possible. Rarely are there breaking changes from one version to the next.
Your pre-existing scripts should be pretty safe 99% of the time. No guarantees of course but like I said, updating is not mandatory.