1. No it doesnt have to be in the index, you can place it in any folder under the web root. example you can have it at
http://www.yourdomain.com/forums if you wish.
Simply login to your adminCP area, change all the paths to point to the new location, and then move all the files into the forums folder
2. Use your customer number and password to login to
http://members.vbulletin.com/ and download the version you had installed.