I believe I still have a script laying around that can import your
vB attachments. The member I created it for basically duplicated some of his forum titles for the gallery, so it just imports the attachments if there is a gallery category with the same name as the forum the attachment is in. If this would be helpful just let me know and I can send you a copy of the script.
Yes, it does give you different permissions settings for each usergroup. If you haven't taken a look already, there is an admin demo that should give you a pretty good idea of the features and such.
http://www.vbadvanced.com/forum/demo/?script=gallery