Lightning strike?

Hello all.
I was wondering how the lightning strike skill works, particularly with the pierce mechanic, and with the projectiles.

Is all of the damage done completely reliant on your physical damage? Or elemental as well.I was also wondering if the iron will skill gem can be applied, because on the wiki (which I haven't the faintest clue if it is accurate or not) it says the projectiles (the lightning, the main part of the skill) is not increased by strength. Next, I was wondering if the damage done by the projectiles would be effected by wrath, or if not, would be effected after iron will was applied.

Lastly, I was wondering how the pierce mechanic works, and if getting something like lightning penetration would be better.

Thanks so much in advance!

EDIT: What about the weapon elemental damage gem, does that effect just the weapon ,or skills cast that use damage from the weapon.Or things like the elemental damae with weapons passives.

bump :<