Launch Files
A Launch File is a file that is automatically "opened" outside of kJams whenever that song is played. For example, you may have Lyrics sheets that are text documents, that you want to be shown when you play a song. Or each song may have it's own "script" that runs, doing something unique, like set stage lighting, or play a movie in QuickTime. Each song has it's own separate launch file.
To set a launch file, select the song and go "Advanced->Special->Set Launch file", and pick your file. You can remove the launch file by "Advanced->Special->Clear Launch file".
Launch Midi Files
kJams currently does not handle "Type 0" Midi files. You can convert them if you like (see link), or you can simply have kJams open an external player to play them. Currently, this is a "secret pref" called "Launch Midi Files", just set it to "true".