1 - Facebook Messenger normally works using a webhook that you need to register with Facebook through a Facebook app. To do this with the Bot Libre AI engine you would need a Java webserver (Tomcat), REST servlet or service, and an https website.
The AI engine is just the AI engine, it does not include a webserver.
See https://www.botlibre.com for free Facebook bot hosting.
2 - This method can be used to poll a Facebook profile or page. It would need to have a Facebook app for authentication. You would need to schedule a background task in your Java program to call this method.