External processes started from NB may need this information to be available via API.
Can't be done. There's no such thing as a fixed list. At least not on most sites these days.
The list you are after is essentially all the inputs for which this script would return "DIRECT". Problem is that such list varies with the result of the .pac file evaluation.
The NetBeans ProxySelector is available throughout the JVM session, no matter if that session is the IDE itself or a NetBeans Platform application. You can ask it questions such as "which proxy to use for this endpoint?". However all standard Java networking calls, such as URLConnection, actually asks the ProxySelector on your behalf and thereby makes a choice on how to reach the endpoint (use a proxy or not, if use a proxy then which one?, etc). It all happens behind the scenes in Java, not NetBeans.