8.5 isn't fully released, and won't be for a few months still. You could still use it, but you may experience issues. As for whether to use it it over 8.2 or 8.3, I would always advise using the latest stable version, as you benefit from all the new features, and maximise the window of support for the actual version of PHP. I believe PHP versions recieve support now for bugs for 1 year and security updates for 2 years, or possibly vice versa. You should treat updates to PHP very similarly to phone updates. Whilst your phone hardward may stay the same, updating adds new features and security fixes, and if you don't update, then you are more likely (even if it is only by a tiny amount) to experience issues or fall victim to securit problems. More on reddit.com

5.6 Zero tests ~14 year old codebase in some parts, most of it is rawdog php and includes. No class structure beyond what we've added for new features. Client actively beligerant at this point to our original agreed goal of them getting 7.x running alongside it on their hardware, and moving portions of the app over as they are worked on, so there's no feature freeze for 12-18 months as it's migrated. They've brought in a second outsourced team as we "aren't moving fast enough" / actually giving a damn to fix security flaws when we find them. This outsourced team is going as well as you'd expect from hearing the term "outsourced team"... Hoping they either get their head out of their ass, or we can cut them off as a client at somepoint. It's just not worth it. More on reddit.com

PHP versions below 8.1 are no longer being supported ( https://php.watch/versions ) i.e. if a bug or vulnerability is discovered in 7.4 or 8, it ain't getting fixed. There's not really any reason to NOT upgrade. Recent versions offer performance improvements. You should always be running up to date WP, theme and plugins anyway - if you're running a plugin or theme that requires php 7.4, it's just a matter of time until you're hacked, because the theme/plugin isn't getting patched. More on reddit.com

The URL given is one that works with the script they provide or expect you to write. There's no built-in "magic URL" to show that information with PHP. A HTML page of configuration information can be generated in PHP code using phpinfo() You may also want to pay attention to the top section of phpinfo() output that lists the ini files read, to make sure you're editing the right files. This same information is available on the command line through the following commands: php -i (full information similar to phpinfo()) php -m (enabled modules / extensions) php -v (version) php --ini (ini files read) See also php --help for more command-line options. Note that you can also set most ini settings at runtime in a script using ini_set() . In this specific case see also the error_reporting() function. More on reddit.com