Is Whited00r safe? If I use it to install iOS 7, can I restore to iOS 4?
Whited00r is not iOS 7. It just looks and feels like iOS 7. You won't be able to install iOS 7 applications or have access to many of the features of iOS 7. You're still running iOS 4 under the hood, and all you have to do is restore in iTunes if you don't like it.