1) when I play Illidan stormrage,will the weapons I have in play remain on Illidan stormrage as he is the new hero?
Equipment doesn't attach to your hero. It just sits in play and your hero can use it. If you had equipment in play when you played Illidan, it will remain there and he can use it.
2)I play blood knight kyria,my opponent interrupts her with nether fracture.I interrupt nether fracture with pummel.
can I heal 4 damage from kyria's effect as I played an ability?
No, unless a card says otherwise, it's powers will only work while it is in play. At that point Kyria is still on the chain waiting to resolve so her power isn't active.
======================
Sweet Zombie Uther!
It's a dirty job, but someone has to do it.