Some Questions on 3.0 RC0

1. Project Area -> Releases
what is the Artifact field for and how is it used?

2. Where can I find examples/doc on Attribute customisation : default
values, value sets, calculated values and validation rules?

3. What is the Effect of Removing row in Quick Information Presentation
Section (eg. Remove SVN link?)

4. How do Widget Catalog Entries show up? I added a new Category with a
Viewlet Entry (eg. Build Duration) in it, but "Add Widget" does not show
this new Category

5. Is there a way to hide the "Enterprise Extensions" node?

Thanks!