If the engine is cranking and won't start, I too would expect something related to the switch considering the mileage.
If the engine is not cranking then it might be the clutch switch that needs adjusting or replacement.
A bad ignition switch could cause the car to stall while driving, but if not the ignition switch then you should certainly look into vacuum problems on the hoses on top of the manifold or possibly a leak from the manifold itself.Someone with a little know how should be able to unplug your ignition switch and start the car with some jumper wires. If it starts right up then you will know the switch needs replacement.