Can't find any info on this, anyone know? example gargoyle magicka cost with expert - master conjuration.

Thanks in advance

I haven't done extensive testing, but I can tell you Twin Souls doesn't work while transformed. There is the Amulet of the Gargoyle, though, which makes you summon two when worn.
As for the other perks, I haven't a clue. I'd assume none work if Twin Souls doesn't, but I've been proven wrong before.

if twin souls doesn't work with 2 gargoyles can you summon a dremora lord then transform and summon a gargoyle?

Do you wear it while in VL form?

Gargoule is Blood Magic. Not conjuration. Thus Twin Souls doesn't work for that ability. It still counts as one of your summon slots how ever. AND when you shift to VL any Dead Thralls with you drop to the ground. How ever, with Twin Souls you CAN Summon two Dremora Lords or what ever else your fav back up is, and then shift and enjoy. You can also have 1 summon out and then call your gargoyl.

Hope this helps