Question

1. Does Life Orb activate after every hit of multi hit moves?
2. Does Life Orb power up all the hits of a multi hit move?
   Multi hit moves are moves such as Fury Swipes, Icicle Spear, DoubleSlap.

Answer 1

I found this on Smogon(it was the first result on Google)

"For multi-hit attacks, all hits are treated as a single attack for the purposes of Life Orb recoil."