Register new user combined with website?

[Doctor Who]

I want to integrate my vbulletin board into the main website for one of my sites. What I need to know though is the following:

1) How can I set up a vbulletin account for that user when they register on the site? (I don't want to have them sign up through the vb registration page)
2) How do I synchronize it so that the current forum users are registered on the main site automatically, and their usernames can't then be taken?
3) What is the best way for me to store the user data that will be specific to the site?

Not sure if this all makes sense, but any help would be appreciated!

[Dismounted]

1./ User Datamanager, there has been numerous threads on this, so search .
2./ Instead of "bridging", an easier way would just be to let vBulletin handle it all, so all the users are in one unified location.
3./ Either a custom profile field, or a separate column in the user table.