Site Wide Categories

Could someone point me in the right direction for this please?

1. I want to be able to set the Categories that are automatically present every new Blog when a new user registers through WPMU.
2. I want to be able to set a test post under one of more of these Categories that can be deleted by the eacch user after sign up.

Is there a Plugin that enables you to set Categories as Admin that are sitewide?
Is there a Plugin for sitewide posts?

Many thanks