The include tag would be fairly difficult to support since it would like require on-the-fly file loading when detected and then using XPath to locate a match. All of that can impact performance since it deals with files at a time you're trying to quickly show a popup. Any time you access a file, you never know if it will load quickly or not.
The navigation feature is complex too. Right now, mouse-initiated quick info hides as the mouse moves over it. Quick info would first need to be refactored to support mouse movement over the popup in that scenario.
The second piece for the navigation request would be to build some link format for identifiers. We have support for links in IntelliPrompt content already. It would have to inject a link for definitions it has resolved instead of just a name identifier. Then you'd have to handle the link click event.
We added suggestions on the TODO list for those items.