Sharing iTunes Libraries

I have about 300Gb of tunes on a usb disk that I have shared on a file server. I'd like to share those MP3s between my iMac, MBP, and my wife's Mac Book Air.

Currently, I have the volume shared, and I've pointed both of our itunes libraries over there. And, things are mostly ok. But, lately I've been doing iTunes cleanup, removing dupes and cleaning up tags. So, now I need to rebuild my library, and that's where I'm running into trouble. If it was just my library, then I'd delete it, and re-add it. But, with multiple people using the tunes, I thought there might be an easier way. So, I'm ready to start over, and I thought I'd ask you guys for your opinion:

What's the best way to share a repository of tunes? I have been pointing the Music Folder Location to the repo, but that seems really slow. Would it be better to just leave the music there, but index it locally?

And, is there an easier way to rescan a library other than deleting everything and re-adding? I hate having to rebuild my playlists.

Thanks in advance!