Authentication methods* customization* pw encryption* and more ?s
 

I have a bunch of questions so I'll order them by importance to me.

1. Does vbulletin make it easy to use outside authentication methods to login to the forums? Specifically my site has its own user management system (similar to WordPress) and I want to integrate the forums to use a single login.
2. Is it simple to customize headers and footers? Ideally I could just insert my site's existing header and footer and "wrap" vbulletin but looking at other sites I'm guessing this isn't easy (even the vbulletin sales site has a separate look and navigation from the forums).
3. How are user passwords encrypted? Our current system uses md5.
4. How does the upgrade / security patch process work? Is it as easy as WordPress? Will it break any customizations?
5. Can users post inline videos using embed codes from sites like youtube?
6. Is it possible to delete all posts by a particular user? Our current forum system gets blasted by a single spammer from time to time but clean up takes a long time to find all the posts.
7. Does vbulletin offer a captcha on the PM system or is it possible for bots to send PMs to members?

Sorry for all the questions at once* I'll try to find the answers to some of this stuff by trying the demo* reading the FAQ* and studying the features list.