1. there are 2 trim devices so as to prevent trim runaway (i'm assuming that you are refering to the 2 switches on the control yoke and not the actual wheels either side of the throttle quadrant)
2. The passenger oxgen system consists of a chemical oxygen generator containing a sodium chlorate charge block. When the mask is pulled a reaction is started which produces pure oxygen. This is mixed with cabin air (possibly to cool it from the exothermic reaction). This makes it usless in a smoke filled cabin.