
Since all lists are regular content your editors can easily maintain all listboxes.

Regular content - well then you can even use autoform to maintain it.

What is stored (and published)
Only the nodeid is stored. Consider it the key.
How do I use the nodeId?
In XSLT you use umbraco.library method getXmlNodeById(nodeid)

Performance - will this kill my webserver?
Nope! It's only accessing the xml file (usually umbraco.xml).
How come you give this away?
I don't know. :o)