iTunes Library and apple TV

I have recently bought my self

- Mac Mini

- Time Capsule

- Apple TV

My objective is to be able to run the mac mini as a media center for the living room television and the apple tv to have access to the movies in a different room.

The point of the time capsule is to serve as an external disk for Itunes + as a backup

My problem is 2 things:

- I want Itunes to use the timecapsule as the data source as it has more space. This works fine, but every time I restart the mac mini itunes defaults back to the original itunes library!

- When in the middle of sourcing a movie on Apple Tv I can suddenly be in situation that the itunes library no longer is availalbe. I believe the problem might be that TC or Mini hibernates and that Apple Tv no longer can get access

What should I do.