2H Axe Lightning Strike build: tips?

So I'm level 37 right now, and using this build so far.



My plan is to go for Infernal Blow as single target DPS, and Lightning Strike as AoE skill. But at the moment I clear packs of mobs way faster with my lower level Leap Slam. I wonder if that's gonna change, considering I have planned a build like the following, with maybe minor changes coming:



So there I picked up the Templar's Catalyse+smaller nodes for 50% elemental damage, but that's about it. The remaining damage nodes I get are for physical damage, and Lava Lash. Will that be enough later so that LS isn't easily surpassed (using this same build) by other AoE skills? Same for Infernal Blow in comparison to Heavy Strike?

Then another important question: as right now it takes me so long to clear packs, would it be a good time to go for Iron Grip already (at ~300 STR right now) to make those 3 projectiles hit harder (don't know if that's worth it yet), or maybe go straight for those Templar nodes?

And the last one: what support gems are nice for LS? I think I will be using sth like Life Gain on Hit, WED, and/or Faster Attacks, but is there any stuff that would help me with the AoE issue?

Thanks for reading all this (and maybe commenting) in advance!