On the cant issue.
If you're shooting off a steady rest, the gun is well benched, your body is sufficiently braced & immobile, and you're pulling the trigger slowly & deliberately, the trigger pull should not be throwing you in any sideways direction.
How does cant work?
Very simply, if you tilt the rifle to the right, you'll shoot to the right.
If you tilt it to the left, you'll shoot to the left.
Intrinsic accuracy involves two facets: One is group size, which won't be affected substantially even if the gun's held upside down, and the other is mating point of impact to point of aim, which is very much affected by the gun's attitude when firing.
The sights are set for elevation to allow for a bullet's upward (arc) trajectory at a given distance. Your muzzle is slightly elevated when you shoot, it's not parallel to the ground. If it were, gravity would pull the bullet down well short of reaching the longer distances a rifle is typically used for.
Fire it upside down and you'll shoot WAY short, since the barrel's now actually pointed at a slight angle down, relative to the ground.
The best way to fix cant is to take the time to correctly align your sight picture dead level & horizontal on each shot.
Eventually it'll become automatic.
Hopefully, anyway.
Denis