[Zubersoft]

No, you can't easily do that I'm afraid. It can be done with database queries, but you'd need a script that would iterate through every setlist, create a new custom group entry with the same name, iterate over every song in that setlist and assign them to the custom group entry. It would not be terribly straightforward to do, and would require some familiarity with writing code along with SQLite queries. You can easily batch edit all of the songs in a single setlist and assign them to a custom group though.

As far as your second question, if you use the custom group field (you have to utilize one of the group fields), then yes, you would be able to use those sorting options. If you just utilize Custom or Custom2, then no, you would not have those sorting options.

Mike