Self propelled artillery in WWII, tactics and communications

[hiperboreus]

Hello to everyone first of all.
I`m interested in any available opinions regarding self-propelled artillery during WWII for the German, Soviet and American sides. How efficient was in combat, what were the tactics employed, communication procedures and direct/indirect fire executed at enemy tanks. Know a bit about the whole thing being a translator for a computer game called World of Tanks. But what it is still missing from my knowledge is actually some sort of statistics regarding the efficiency of direct/indirect fire (how many shots for a confirmed kill), theatre of war disposition (SPGs employed at a certain distance from main tank force or it were integrated). Have studied quite a few materials regarding this but the general opinions are still a bit blurry.
Any help would be appreciated as maybe you can shed some light regarding all this. Hope that would find here a couple of WWII enthusiast researchers:hitwall

 

[My2Cents]

Please clarify -- Are you interested in self propelled artillery for indirect fire (such as the Wespe, Hummel, and Priest), or self propelled assault guns and tank destroyers using direct fire (such as the StuG-III and SU-76)? Most vehicles only perform one role well.

 

[hiperboreus]

Please clarify -- Are you interested in self propelled artillery for indirect fire (such as the Wespe, Hummel, and Priest), or self propelled assault guns and tank destroyers using direct fire (such as the StuG-III and SU-76)? Most vehicles only perform one role well.

Wespe, Hummel, Priest would be a good start. Thank you