Facets vs Artifacts

Is there any documentation for the difference between these two?

I'm trying to write my own appserver integration (against the bundled EE stuff), but it looks like all the old stuff that referred to facets now refers to artifacts. Setting up a project is a bit more of a hassle now as a user has to add a web facet as well as a web artifact, as it seems like only artifacts can be deployed now. I'm assuming this is intentional and there's no way to write appserver integration against a facet anymore?

Secondly, given a web artifact or javaee app artifact, how do I ask it stuff like 'give me your configuration files (application.xml/web.xml)', or finding out what the root path to it is?