The red button is the fuel inertia cut off. Do you have to keep resetting this now? Do you do a lot of town type driving as if so this could block the catalytic convertor. If so then when started take the car for a motorway/dual carriageway drive for at least 30 mins and keep the revs above 2000 rpm. This may then help. As for difficult starting this may be a different problem. Has the fuel filter ever been changed? It may be prudent to have a diagnostic carried out to see if a fault code exists before you go changing any parts, as the problem could be one of many things such as a faulty engine coolant temp sensor, a fuel pressure/rail sensor, EGR problems, the solenoid/valve or the injectors.