1) Is the tyre pressure on the door jamb the MINIMUM recommended pressure when the tyres are cold? My car states 235kPa for front & rear

2) I read that altering the tyre pressure slightly can affect the handling profile, e.g. increasing pressure at the front to reduce understeer, decreasing pressure at the rear to increase oversteer

Would it be safe for me to have the front at 240 & rear at 225 to reduce understeer or 245/250 & 235 if the pressure on the door jamb is indeed the minimum?