i'm with chris, gentle way to get it off. if you mess with the starwheel like IJ said you will have to adjust it when you put it back on. and besides, if the e-break is off it shouldnt be contacting the rotor to hold it on.
adjusting it would be putting the rotor on then adjusting the starwheel untill the shoes just contact the hat. and then backing the starwheel out a click. make shure it turns freely while still clamping on the hat nice and hard when the e-brake is on.
try some penitrating lube, might be rusted on. or if your replacing the rotor just do what i did and use a pry bar and or a hammer.
Edit: i just went back and read your first post. the answer is no. the nut with the cotter pin does not need to come off to pull the rotor. once you get the caliper/torque plate off the rotor can just slide off. maybe not easily, but i can just slide off.