Does the Casper theme and default way AMP pages are created include support for Analytics?
Specifically, if I use the code injection at the site level in Ghost Admin, will that tracking carry over into the AMP pages or do I have to create a custom hbs file in order to track AMP data?
Analytics in AMP pages do not work with the same script that you usually use for Analytics. Accelerated Mobile Pages require a different Analytics tag.
Here are a few links that might help you understand how to set Analytics for AMP pages:
Tracking Accelerated Mobile Pages (AMP)
Adding Analytics to your AMP pages
AMP Analytics by example
Analytics and AMP - How to Track ALL THE THINGS (AMP Conf 2018)
The best way to do this is to save the amp.hbs file:
Put it into your theme folder. Do the required changes and it should work.
After you do your changes be sure that everything is validated. To do this add #development=1 to the URL of the page. You will see your errors, if you have, in Console tab. Debugging.