Is it possible to remove this content after it's served it's purpose of allowing the $pdf object's items and groups to be populated?

This isn't implemented. I've put this to the backlog so we take a look later if we are able to remove these hidden text blocks from the pdf. Thank you for the idea.
https://github.com/jsreport/jsreport/issues/626

In general, it would be great if jsreport offered some capabilities of making the generated PDFs more accessible.

Have you tried this extension https://jsreport.net/learn/pdf-meta ?

Is there any way of adding top/bottom margins when non-forced page breaks occur?

You mean that page breaks splits the table and you want a top margin to the second part of the table.
I think thead tag should be repeated and maybe you can put a margin on it. However, I haven't tested it.
Nothing else comes to my head now,

Does jsReport add any extra magic to the chrome-pdf recipe, making this a non-working concept?

There is no magic. jsreport in the end just asks chrome to convert html to pdf.

The specificity of @page without other selector keywords is (0,0,0), so it should be overridden by @page a-page-name

I am afraid that the @page css3 selector isn't fully implemented in the chrome. So the spec for printing pages and counters isn't yet covered there. That is why we implemented pdf-utils to allow you to merge pdfs together and achieve more complex things.

You can use none templating engine to avoid templating engines evaluation.

You can use html recipe and do normal render request through the API.
Some problem with that?

I tried the mentioned steps with your account and it works.
Don't you run behind some kind of proxy?
What browser/version do you use?

Is it mean that I can host several jspreport applications in one server?

No. The enterprise license key can be used only on one production jsreport instance.

Is it mean that I can apply the key in several server like DEV, UAT, Production. DEV and UAT is only for development teams, and PROD is for client user?

We don't say what is DEV or UAT environment. We just say that jsreport enterprise license key can be used for free on the environments that are not reachable by users outside dev team. So you can buy single jsreport license for your production server but your developers or some automated testing servers can use it as well.

The url will be something like localhost I guess. You can make your own web server, put there an image and check how the host looks like when it is requested by jsreport/chrome.

I think should IP addresses for the restriction. The url isn't secure anyway. The ip address will be the same as your EC2 ip.

You are probably having more than 5 templates in the store and don't have a proper license.
If this is the case, you need to remove some templates first in order to start the instance again.
Open data directory and delete templates you don't need. (Backup the first)

Hi,
you can apply license key on your local jsreport instance.
It will at the first start create file jsreport.license.json which you can copy-paste to the root directory of your production isolated instance.

Try to run jsreport.exe with proper working directory

cmd /c "cd /d d:\pathtoworkingdir && d:\pathtoexe\jsreport.exe start"