Use some software, there are free ballistics programs available on the internet. A bullet throughout it's flight is subjected to the constant force of gravity, an accleration of about 10m/s^2 downwards, so the total drop ends up being a function of flight time. A high velocity bullet drops less than a slower one at the same range because it reaches the target quicker and therefore spent less time dropping.
A device that allows you to compensate for bullet drop
Gravity.
There is no one answer, since there is no one bullet. The drop of a bullet is a function of the speed- how long it took to get to 1000 yards. Some bullets will not TRAVEL 1000 yards. All other things being equal, the faster bullet will drop less.
yes
as far as it wants
Sorry, you need to specify WHICH .308 bullet and at what distance. As distance increases, the RATE of drop also increases.
The same as any metal.
not much
Due to gravity, the bullet starts to drop the second it leaves the barrel. You can calculate the drop by factoring mass and velocity with gravity (9.8 m/s²).
To the ground.
No such caliber. Sorry. If you man the Lapua .338 Magnum, drop will depend on the ballistic coefficient of the bullet being used, it speed, etc.
The BULLET drop is the pull of gravity on the bullet as it is shot, resulting in the bullet lowering in altitude over a long distance. This is what long-distance shooters have to account for on their scopes. Different types of bullets with different weights, sizes, and shapes, as well as the barrel length and rifling ratios, affect how much the drop will be.