Distance at regulation only accounts for elevation.
The sights are usually marked with distance.

The question of which bullet type or weight is usually answered by the conventional loading of the cartridge - and when it's not standard the rifle is sometimes marked with the proper load.
You might find some clues in the Proof-House marks too.

What rifle specifically are you discussing?

On the issue of different bullet types for the same rifle, some rifles and some calibers are more forgiving than others, also some rifles feature adjustable barrel regulation.

Cheers
Tinker