6 intriguing questions on Carnage

[Sotnik]

Hi! 
Carnage allows to deal "33% of Base Weapon Damage in Area on Weapon Hit".
1) Does that mean Carnage procs on Hit and Crit and does not proc on Graze?
2) What is Base Weapon Damage? Does that mean the damage is not modified by an active ability if I use one? What other modifiers do not work here? Is the damage somehow affected by the final amount of damage dealt to the primary target? Does Carnage use separate hit rolls? 
3) Does Carnage trigger effects requiring successful weapon hits/crits, including buffs?
4) What is the base angle/range of Carnage?
5) Does Carnage scale with the character or power levels?
6) Does Carnage affect the primary target?

Edited May 12, 2018 by Sotnik