No, it's a 2-hander - hence putting it in the cube. (Did you click on the link I posted?)
Yep - just like the arcane immune amulet protects you in the DH Shadow dungeon and the cold immune one protects you in Firebirds. You don't need immunity but it's one less thing to worry about or that can screw you over at the last minute.
I only wish there was a physical immune amulet that I could use for freaking Wastes