Mbp+ipad+mac mini+time machine home network setup help

Any suggestons on a slick way of setting these all up to play nice with one another?
My general wish list -

1. To be able to buy a song or movie on one device and quickly send it to another without then need to do a complex sync.

2. To be able to easilly share files with one another quckly and easilly

3. To use the mac mini server as the main file repository

I realize these are pretty general needs but figured someone would have setup that achieves all this and would like to share how to put it all together cleanly.

The absolute easiest way is to use dropbox or sugarsync - which will also allow you to access the files from anywhere.
Dropbox - Online backup, file sync, and sharing made easy.
http://www.sugarsync.com

Dropbox has a folder that syncs with the cloud and you get 2GB of free space.

Sugarsync has a smart folder in documents that syncs and you get 5GB of free space.

All files are synced across all computers seamlessly. Both have Apps in the Appstore.

The hard pard is the iPad. There are other ways to move files around but with the iPad in the mix - one of the cloud options is probably the best way to have files synced.