Do Illusions have all passive abilities as my hero has? Even from items?

Yes and No, Illusion benefits from a lots of passive abilities may they be granted by items or skills but not all.

You can not benefit from bashes on illusion (Bash from basher, Abyssal blade, or Barathrum's bash for example). That would be way too powerfull. For the same reason, Feedback (diffusal blade's orb effect) works on illusion but only melee one.

You can take a look on the Illusion page of the wiki which give a quite exhausitve list of the passive your illusions benefit (or dont benefit) from.

Illusions do not benefit from item raw damage or attack speed, they benefit only from item stats (int, agi, str) or auras such as radiance's or vladimir's. Note that they bestow the aura, but may not benefit from it, which is the case of the lifesteal aura from Vladimir's.

The only orb effect that works on illusions is Diffusal Blade feedback orb, and this is for melee heroes only. Also it is worth noting that illusions get the critical chance from Daedalus/Crystalis, but not the raw damage.

As for passive abilities, yes, illusions do benefit from most of these. For example, Chaos Knight's illusions have Chaos Strike, and Mortred's illusions (if one have Manta Style) have Blur and Coup de Grâce.