Andrew Benson can be contacted from the Chex Quest fan forums (IIRC he's Druben there or a name like that).
For the Heretic tunes, maybe Kevin Schilder would respond to an email?
Other songs I'd suggest would be Mustaine's stuff on Perdition Gate and Hell to Pay. Here too, though, titles are missing as far as I know.
A possible solution to the title issue, if people don't reply to emails, would be to name them after the first level in which they're used.