Can iTunes Match grab "invisible" (placeholder) songs? I have a drive which has a folder full of MP3s on it. At one point, I added all of these MP3s to my iTunes Library; sometime after that, my folder turned into a Unix executable file.

My question is this: If I turn on iTunes Match and point it at the list of songs I have in my library -- as the list is still there, even though the files themselves can't be found -- will it scan the info saved in iTunes and use that to match with songs in the cloud? Or will it need the actual files, from which it can scan metadata to check in Gracenote?
iTunes Match matches based on the audio fingerprint of the files, simply having the metadata won't do. The process has nothing to do with Gracenote's metadata in any form. If it was just based on the metadata, you could change it and pretend to have whatever songs you want, and clearly that's something Apple wouldn't want you to be able to do.