Data Leak Prevention software for mac OSX
You don't really describe how your software works, but if you work with an app like Exces (that make it easy to work with, but the feature is available to OS X without the software) you can always work on an encrypted image and close it after use.

Of course you can use Filevault as well to maintain your filesystem encrypted. 

Sadly, these have nothing to do with number three, since that is network dependent.