Vodafone unlock handsets free of charge now.
Take a look on their forum, and use the instructions to get in contact with their eforum team.
I have had several blackberrys unlocked by them, but I am a customer, so I don't know if that makes a difference.
Crackberry is a very good site.
In terms of debranding, I don't think you can actually remove the operator splash screen at start up. You can however load the latest version of the Operating System from any carrier, but you will need to follow the instructions over at crackberry.