Sounds like this is unique to you and your system? I've been using Firefox for casual browsing for years and I experience none of these issues. As in I don't even know what you're referring to honestly because I've never seen such things in all these years of having it. Chrome is set as my default browser btw.

The only "pop-up" - if you can call it that - I ever get is the one telling me a new version of FF is available for download.