In order for most notifications to work you need a working CRON process http://learn.elgg.org/en/stable/admin/cron.html

Also make sure you wish to receive site notifications about a person or group in your notification settings.

In order to check if your cron is working you can check the admin widget on the admin dashboard or got to http://yoursite/admin/cron

Your solution should work.

Keep in mind that depending on how you create the temp file within PHP if you close the filehandler the file is removed.

You could also provide the ElggFile to the attachments array, or provide an array with 'contents' which is the content of the (temp) zipfile.

See https://github.com/Elgg/Elgg/blob/52a0189a68205290cfac02b13d7ab65ab26e72a4/engine/classes/Elgg/Email/Attachment.php#L23-L39

https://github.com/beautylix/contentinsert

Version control is a very broad concept. Which do you mean?

Version control for plugin code can be done on many platforms like GitHub, GitLab, SourceForge, etc. If you want to know how to use those search on their websites.

If you mean easier management of how your plugins and Elgg are installed on your website you probably mean Composer. Check their website of how to use that tool https://getcomposer.org/doc/00-intro.md

When using Composer to manage you plugin versioning have a look at the Elgg starter project for a good basis on the initial Composer setup. https://github.com/Elgg/starter-project

You can also put your Composer configuration (based of the started project) in a code versioning system that way you can easily revert changes.