Skeletons damage conversion

Hey, I'm a casual SSF player, who plays pretty much the same build every time - I just stick Zombies and (Vaal) Skeletons on the same 6-link and do physical damage. I got a weapon with the last node being "summon skeletons and holy relics convert 100% of their damage to a random element, with 100% effect of non-damaging ailments." With my support gems being physical, will they increase the elemental damage?

I saw in the wiki that it will - it says Damage conversion is done before any increases, or multipliers are applied to damage guaranteeing that they are only applied once. However, converted damage is affected by modifiers that apply to both the original damage type it was converted from, and the new damage type that it was converted to.

Does it really work that way? So I should take that node? And if I go only skeletons without zombies, with elemental support gems, will that increase the damage over keeping physical?

You'll be fine without switching. Just don't play Brutality support.