#1
What scales shall I learn that are useful in Metal?

I know major and pentonic so far.

longing rusted furnace daybreak seventeen benign nine homecoming one freight car
#2
different minor scales
and pretty much all major modes
GEAR -
Gibson Les Paul VOS '57 gold top
ESP LTD MH-250NT
Vox AC15
#5
why not just learn them all? you can apply nearly everything to metal solos if you play it quickly, the more you know the more you can do, learn everything in every key too.
#6
Learn the natural minor, its easy if you know the major scale and understand relative minors - then its really easy to learn melodic & harmonic minor from that