a) What will be the file naming convention of the individual UDL’s?
the file name can be literarily anything.xml.
the included udl or multiple udls in this “collection” do not have to match the .xml file name.
b) UDL’s are user settings. Are user settings located in the AppData area and not in Program Files?
yes, they will be created at %AppData%\Notepad++\userDefineLang.xml, and can be moved/copied/renamed to %AppData%\Notepad++\userDefineLangs\.
this folder will probably be the preferred location for a future deployment of a descriptive yourUdlCollection.xml, instead of overwriting an existing userDefineLang.xml.
c) Should the Auto Complete files, which are considered user settings, (also) be located in the AppData section?
this is a tricky question, because on one hand they are currently located at %ProgramFiles[(x86)]%\Notepad++\autoCompletion, but on the other hand it would make sense to allow a user specific version at %AppData%\Notepad++\autoCompletion\ which is, afaik, currently not implemented.
d) I wish to package together the UDL file(s) and Auto Complete file(s) as one zip file. Will there be file name conflicts?
with the new udl collections: no, as they can have any names, and don’t reside at the same location as a default userDefineLang.xml.
with the autocompletion.xml files themselves yes, as a same name xml, like html.xml, would replace the existing file at %ProgramFiles[(x86)]%\Notepad++\autoCompletion.
note: this information is based on the current pre-release builds, with the newest udl features already implemented.
anything currently known, might (or might not) still be subject to change.