On a hunch I renamed “jingleNodes_i18n.properties” to “jinglenodes_i18n.properties” and restarted openfire. There are now no question marks. Linux is case-sensitive, and windows is not. The Jingle Nodes Plugins provides org.jinglenodes namespace, so I suppose it was looking for a corresponding language file.
Now I can read properly the plugin features, and can answer some of my own questions:
2] To change the port range, edit the source and rebuild the plugin. From what I can tell http://xmpp.org/extensions/xep-0278.html jingle nodes can use any port range.
3] Ignore this, it is autodetected, I misread the question marks.
Anyway, from what I can tell, this jingle nodes plugins provides both an XMPP relay (explains the “active channels” information field) and tracker. Which means, basically, plug and play: openfire media services should be disabled since jingle nodes provides a standalone relay, and clients do not need to manually add a list of jingle node relays, since they can just query the jingle nodes plugin.
Unfortunately, I have yet to get the Jingle Nodes Plugin to work…