1) Can't help a lot here. Need to get you a Service manual or at least an Owner's manual so you know Maint, Specs and such.
2) OFF - No Fuel flowing
ON - Fuel flowing (Ride at this setting)
RES - stands for "Reserve" (Flip to here if you run out of gas)
Again, ride in the ON position - if you run out of gas, flip over to RES to get several more miles to hopefully a gas station.