Hi I recommend that you update to the latest ESR as a minimum for your daily driver. Currently ESR is version 91, but is expected to update to 102 soon. Checking for updates in the terminal would be the swiftest way to make sure you have the most recent version from the Debian repos. Firefox Developer Edition is a very good choice - it is a couple of versions ahead of the regularly updated Firefox that your users will have and will best to help make sure that web content you are making works for them.