You should be able to change the settings for .mp3 files in Control Panesl>File Exchange.

This problem can also be resolved with a little program called Snitch. It's shareware for $20 and the best money I ever spent. I have all of my music files set to download as Quicktime Files so I can test them with Quicktime before adding them to ITunes. I then use Snitch to change them. Insofar as those music files with long names, I shorten them so I can add the .mp3 extension and then expand the names in ITunes. Just highlight the song and "Get Info."

There's more than one way to skin act but this works for me.