1.he does not have to see the impact point;2."Living Avalanche : Attack Attribute - Attacks & Weapons. Impact Hits from the model gain +1 Strength and +1 Armour Penetration"
"Devastating Charge (+1 Str , +1 AP)"
[refer to the unit entry for further detail]
So he has S7 on the charge, and his impacts get +1S, which means the impact hits are at S8.
Impact Hits are Special Attacks, and the Devastating Charge special rule only affects Close Combat Attacks (i.e. the number under Att in the unit profile). So the Impact Hits are resolved att S7.
So, according to this, chariots have allso basic strength impact hits? For example chariots in undying dynasties have S4 or S5 hits? Chasis have S4 and devastating att+1S. Cause ogres have special rule living avalanche, it means every model must have stated specially by some rule that +1s form devast. charge aplly to impact hits?
Another example is the OK Big Name Spineplitter.