That is correct, it will XFA Based PDF

Two subsequent dispatchers are not even a supported topology. You should not consider this scenario.

I agree with albinissac Two subsequent dispatchers are not a proper configuration. If you have multiple sites that need to be accessed as different sites you can use a single Apache.Please review KB at https://docs.adobe.com/content/help/en/experience-manager-dispatcher/using/configuring/dispatcher-...

AEM Forms is the solution for interactive PDF (XFA based). Adobe best practice for an interactive PDFs is AEM Forms Designer. As I mentioned you need to set margins in Layout.

Hard to make recommendations for third party software. Adobe Managed Service (AMS) best practice is Splunk and New Relic.

Content paths can either be invalidated or flushed from the AEM Dispatcher cache.AEM Dispatcher behavior - invalidate performs a cache invalidation, similar to when content is activated from author to publish (CQ-Action: Activate, CQ-Action: Deactivate) flush performs a cache deletion (CQ-Action: De...

Are you referring to an AEM Forms and therefore to a form's pages? If it's correct, then margins can be set in layout https://docs.adobe.com/content/help/en/experience-manager-learn/forms/ic-print-channel-tutorial/partfour.html

You can possibly upload Captivate projects into a DAM as an asset. That can be done via TouchUI, WebDev or AEM Desktop App. Check if you need to ZIP the entire project and extend the DAM Update workflow with an Unarchive step.

You can create a minified version of your libs outside of AEM and deploy it along with your project. Although, it will limit an ability to recompile libs at runtime

AEM on-prem has a lot of ob built-in tools that allow successful monitoring while using the product.Health reports are gathering information on an AEM instance through Sling health checks and allow a custom dashboard deployment.You can even take advantage of an OOTB Monitoring Charts https://docs.ad...