What is the stink you smell when accelerating? Raw fuel? Exhaust?
The p1450 refers to excess vacuum in the evaporative system.
The p2196 refers to O2 Sensor 1 biased/stuck rich, which means there's too much fuel. The P2196 code can be caused by a failed oxygen or mass air flow sensor, sensor circuit problems, fuel system problems, Evaporative Emission Control System (EVAP) issues, or a bad PCM.
p0420 says the O2 sensor detects lower than desired O2, and can also indicate a fueling problem.
If the smell you get is a fuel smell, all that points to a fuel problem. Since one code refers specifically to the evaporative system, I would say that is the primary cause of your problem. Either need a new canister or there's something wrong with the hoses and/or valve that are up front. Or maybe both.
Typically the bad canister doesn't cause raw fuel smell in the cabin. So I'd be concerned that there's some kind of overfueling problem in the engine compartment.
As an aside, the problem with stumbling/dying after fueling the car usually involves topping off after the pump initially shuts off, plus not giving the system time to settle down and vent before closing the gas cap (which happens when you pull the pump nozzle out of the gas filler). With the Fiesta ST you MUST NOT top off the gas, and you MUST leave the filler nozzle in the filler for a period of time-perhaps 15 seconds-before removing it.
