Sync Library Only

Hi, I've read lots of other threads on this issue but cant get a thorough answer on this:

I recently moved all of my music files and my wife's music files onto a 1TB external drive, attached to the back of my time capsule. Using an automator script, we can each mount the drive from wherever. So, we have deleted music from our individual macbooks. I was able to create one large library.xml file out of our new music folder (I reatined metadata from my music).

My understanding was that if I moved the library to the external drive, we could have corruption issues if we both try to access and change the library at the same time. So, I have retained two separate LOCAL library folders....one on each laptop. In theory, these should be identical though.

Keeping the actual music files together is easy. Either of us can drag/drop music into itunes, and as long as the drive is mounted, itunes will suck it onto the external. But keeping the libraries in sync is the issue.

My questions:

(1) Assuming we continue to place the actual music files into the correct external drive, is keeping the local itunes libraries in sync as simple as using syncing software to sync between our two laptops the itunes library.xml, itunes library, itunes library extras.itdb files?

(2)Would it just be easier to keep the library on the external as well? If so, how can we both access the library at the same time?