Toy Box Sharing Questions

sorry of this has been asked and answered elsewhere (if so and there is a share/download FAQ somewhere, please point me to it)

Where do you go to download/see toy box creations other people have made?
If you download one, and it has something in it you haven't unlocked, how does that work?
Where is everything stored when you download it? Will me system have to bee online to use other people's creations?

thanks

~James