Module development and code questions

Hello.

First, I need to say that I'm a complete newbie on Drupal so, sorry if my question is stupide. 

I have a question (need help) regarding element in webform (and how to create a more complex one if it's possible)

First, I was positively surprised to see, on the text field element, that it's possible to have prefix and suffix. In English, the $ goes before an amount but after if the form is in French. (it would be useful to have a separate space for currency that would switch side automatically, depends on the language used

I'm trying to understand the best way to loop through a paragraph field within the node.html.twig file. That is if there is a way. For some reason I'm having a hard time wrapping my head around this part.

Here's an explanation of the setup:

In my content type, I have a paragraph field called Main Topic. The Main Topic can be added multiple times and within the Main Topic another paragraph can be added, which defines all of the sub-topics and their descriptions. (Note: this is an inherited project so changing how the fields appear is not an option). 

Hello - I was advised that in php.ini, I should set variables_order to "CS" only because we should not use the super global arrays for $_GET, $_POST, $_ENV, and $_REQUEST.  However, if I set variables_order = CS, Drupal core no longer functions correctly.  In particular, the login form on Drupal (core) no longer works.  It does not log in the user and just refreshes the page.  Per php.ini documentation, using those super global arrays creates extra overhead.  Also, per https://www.drupal.org/project/drupal/issues/

I try to port a module that i want to publish, to Drupal 11. 

There have been some changes to the API and i cant get it to work at all. It must be some small detail in namin of something.

I still get:

• 'elif_nofollow' is not a supported key.
• 'elif_noopener' is not a supported key.
• 'elif_noreferrer' is not a supported key.

I have a custom text filter like this:

What are the best ways to audit and review a custom module (or a contrib module) to ensure it is secure, or at least follows best practices?