Just read your original post again. Maybe there isn't an absolute "audio_credits = project-1"?
Try some wildcards - search="audio_credits = %project-1%"
What you are asking for would best be handled by a new 'Invite' module.
Jamroom doesn't have one atm and unless there is more demand its not likely to be high on the 'to do' list.
But it might be a straightforward adaptation using jrNewLetter as a starting point should you want to check it out yourself?
The jrEmbed module should allow you to embed jrAudio (and jrVideo/jrGallery/jrFile etc.) items into a blog (and any other editor field).
There are functions in the modules to enable this, so if Nate's module includes these, that player should be embedable as well.
hth
Pa