You should have your armor, yeah.
No, the first 4 orks were all killed.
No extinguisher in sight... most likely place (if the ancients followed security procedures, which is doubtful) would be inside the truck's cabin... which is also on fire.
As for the box, I'm not 100 percent sure utility box is what it's called... If you do, let me know. It's the kind of box with a lot of electrical wires and fuses. Don't expect to get anything out of it.