Are you aiming for the more clean wide/high range that is in a lot of prog metal? If that's the case you may want to try looking around for someone who is a retired metal/rock vocalist but is now primarily a vocal coach.
(side note - anyone remember the Mythbuster's episode with the guy that broke the wine glass with his voice?
As for vibrato, I believe that's actually frowned on if you're learning proper singing technique. It's more of something that added in because it sound pleasing to our ears. Supposedly it can mess up a person's vocal cords though?
Somewhat unrelated... but I recently discovered I can easily do a black metal rasp growl.
No one will ever hear that, though.