Hey there, have you taken a look at the gameplay statics functions?
Take an Actor BP, for example, head over to the MyBlueprint tab, under Functions, if you hold your mouse over the “+” you can deploy the “Override” submenu with a bunch of built-in functions/events you can use. Have a look at the Apply Point Damage one; you can pass a lot of information through that event, including a Hit variable which you can use to calculate those dot products via the impact normals and positions. You can also use this event to pass along your own Damage Class that you could use to make further calculations for velocities and impact forces.
Cheers!